"""Ops and optimizations for using BLAS calls

BLAS = Basic Linear Algebra Subroutines
Learn more about BLAS here:
    http://www.netlib.org/blas/blast-forum/
The standard BLAS libraries implement what is called "legacy BLAS" in that
document.

This documentation describes Theano's BLAS optimization pipeline.

Where there is a discrepancy between how things do work and how they *should*
work, both aspects should be documented.

There are four kinds of BLAS Ops in Theano:
    - Python implementations (this file)
    - SciPy-based (blas_scipy)
    - C-based (blas_c)
    - CUDA-based (theano.sandbox.cuda.blas)

:note: Unfortunately (because it's confusing) this file currently contains Ops
    that contain both Python and C versions.  I think it would be better to
    move the C implementations to blas_c so that this file is pure Python.
    -JB


Ops
===

GEMM: Dot22, Dot22Scalar, GemmRelated, Gemm
-------------------------------------------

The BLAS GEMM operation implements Z <- a X Y + b Z,
where Z, X and Y are matrices, and a and b are scalars.

Dot22 is a GEMM where a=1, b=0, and Z is allocated every time.

Dot22Scalar is a GEMM where b=0 and Z is allocated every time.

Gemm is a GEMM in all its generality.

In the future we can refactor the GemmRelated, Gemm, Dot22 and
Dot22Scalar Ops into a single Op.  That new Op (Gemm2) is basically a
normal Gemm, but with an additional configuration variable that says
to ignore the input Z.  Setting that configuration variable to True
would make Gemm2 equivalent to the current Dot22 and Dot22Scalar.
This would make the file a lot easier to read, and save a few hundred
lines of library, to say nothing of testing and documentation.


GEMV: Gemv
----------

The BLAS GEMV operation implements Z <- a X Y + b Z,
where X is a matrix, Y, and Z are vectors, and a and b are scalars.


GER: Ger
--------

The BLAS GER operation implements Z <- a X' Y + Z,
where X and Y are vectors, and matrix Z gets a rank-1 update.


Other Notable BLAS-related Ops
------------------------------

SYRK is another useful special case of GEMM. Particularly SYRK preserves
symmetry in the matrix that it updates.  See how the linear-algebra module uses
symmetry hints before implementing this Op, so that this Op is compatible with
that system.


Optimizations
=============

The optimization pipeline works something like this:

    1. identify dot22 from dot
    2. identify gemm from dot22
    3. identify dot22scalar from dot22 that are not gemm
    4. specialize gemm to gemv where applicable
    5. specialize gemm to ger where applicable
    6. specialize dot22 -> gemv or ger where applicable

:note: GEMM is the most canonical BLAS signature that we deal with so far, it
    would be good to turn most things into GEMM (dot, inner, outer, dot22,
    dot22scalar), and then to specialize from gemm to the various other L2 and
    L3 operations.

Identify Dot22
--------------

Numpy's dot supports arguments that are of any rank, and we should support that
too (just for compatibility).  The BLAS optimizations work with Dot Ops whose
inputs are each either vector or matrix.  So the first part of the optimization
pipeline is to transform qualifying Dot Ops to Dot22 Ops. Dot22 Ops may be
transformed further, but they will get implemented by a BLAS call.

More precisely, Dot nodes whose inputs are all vectors or matrices and whose
inputs both have the same dtype, and whose dtype is float or complex, become
Dot22.  This is implemented in `local_dot_to_dot22`.


Identify Gemm from Dot22
------------------------

This is complicated, done in GemmOptimizer.

Identify Dot22Scalar from Dot22
-------------------------------

Dot22 Ops that remain after the GemmOptimizer is done have not
qualified as GEMM Ops. Still they might be scaled by a factor, in
which case we use Dot22Scalar which is like Gemm, but without the b
and the Z.  In the future it would be good to merge this into the
GemmOptimizer.

Specialize Gemm to Gemv
-----------------------

If arguments to GEMM are dimshuffled vectors, then we can use GEMV
instead. This optimization is `local_gemm_to_gemv`.


"""
import copy
import logging
import os
import sys
import time

import numpy
import numpy.distutils

from theano.configparser import config, AddConfigVar, StrParam
from theano.gof import (utils, Op, view_roots, DestroyHandler,
                        local_optimizer, Optimizer,
                        InconsistencyError, toolbox, SequenceDB,
                        EquilibriumOptimizer, Apply,
                        ReplacementDidntRemovedError)
from theano.gof.cmodule import GCC_compiler
from theano.printing import pprint, FunctionPrinter, debugprint
from theano.compile.mode import optdb
from theano.gof.python25 import all, any
import theano.scalar
from theano.tensor import basic as T
from theano.tensor.blas_headers import blas_header_text
from theano.tensor.blas_headers import blas_header_version
from theano.tensor.opt import local_dimshuffle_lift

_logger = logging.getLogger('theano.tensor.blas')

try:
    import scipy.linalg.blas
    have_fblas = True
    try:
        fblas = scipy.linalg.blas.fblas
    except AttributeError:
        # A change merged in Scipy development version on 2012-12-02 replaced
        # `scipy.linalg.blas.fblas` with `scipy.linalg.blas`.
        # See http://github.com/scipy/scipy/pull/358
        fblas = scipy.linalg.blas
    _blas_gemv_fns = {
            numpy.dtype('float32'): fblas.sgemv,
            numpy.dtype('float64'): fblas.dgemv,
            numpy.dtype('complex64'): fblas.cgemv,
            numpy.dtype('complex128'): fblas.zgemv,
            }
except ImportError, e:
    have_fblas = False
    _logger.warning('Failed to import scipy.linalg.blas. '
            'Falling back on slower implementations (%s)', str(e))


class Gemv(Op):
    """
    expression is beta * y + alpha * A x

    A is matrix
    x, y are vectors
    alpha, beta are scalars
    output is a vector that can be inplace on y
    """
    def __init__(self, inplace):
        self.inplace = inplace
        if inplace:
            self.destroy_map = {0: [0]}

    def __eq__(self, other):
        return type(self) == type(other) and self.inplace == other.inplace

    def __str__(self):
        if self.inplace:
            return '%s{inplace}' % self.__class__.__name__
        else:
            return '%s{no_inplace}' % self.__class__.__name__

    def __hash__(self):
        return hash(type(self)) ^ hash(self.inplace)

    def make_node(self, y, alpha, A, x, beta):
        y = T.as_tensor_variable(y)
        x = T.as_tensor_variable(x)
        A = T.as_tensor_variable(A)
        alpha = T.as_tensor_variable(alpha)
        beta = T.as_tensor_variable(beta)
        if y.dtype != A.dtype or y.dtype != x.dtype:
            raise TypeError('Gemv requires matching dtypes',
                            (y.dtype, A.dtype, x.dtype))
        if A.ndim != 2:
            raise TypeError('gemv requires matrix for A', A.type)
        if x.ndim != 1:
            raise TypeError('gemv requires vector for x', x.type)
        if y.ndim != 1:
            raise TypeError('gemv requires vector for y', y.type)
        if y.broadcastable[0] != A.broadcastable[0]:
            raise TypeError('broadcastable mismatch between y and A',
                            (y.type, A.type))
        # The following is not grounds for error because as long as
        # sizes are 1 at time of perform() there is no problem
        #if x.broadcastable[0] != A.broadcastable[1]:
            #raise TypeError('broadcastable mismatch between x and A',
                             #(x.type, A.type))
        return Apply(self, [y, alpha, A, x, beta], [y.type()])

    def perform(self, node, inputs, out_storage):
        y, alpha, A, x, beta = inputs
        if have_fblas and y.shape[0] != 0 and x.shape[0] != 0:
            gemv = _blas_gemv_fns[y.dtype]

            if (A.shape[0] != y.shape[0] or A.shape[1] != x.shape[0]):
                raise ValueError('Incompatible shapes for gemv '
                        '(beta * y + alpha * dot(A, x)). y: %s, A: %s, x: %s '
                        % (y.shape, A.shape, x.shape))

            #Here I suppose that A is in c order. If we don't make it
            #  explicitly as fortran order, scipy 0.7.2 seam to create
            #  a copy in fortran order instead of just reshaping it
            #  and using the trans flag.
            #If A is already in fortran order, make it in c order and using the
            #  trans flag don't seam to cause slowdown.
            #out_storage[0][0] = gemv(alpha, A, x, beta, y,
            #                         overwrite_y=self.inplace)
            out_storage[0][0] = gemv(alpha, A.T, x, beta, y,
                                     overwrite_y=self.inplace, trans=True)
        else:
            out = numpy.dot(A, x)
            if alpha != 1:
                out *= alpha
            if beta != 1:
                out += beta * y
            else:
                out += y
            out_storage[0][0] = numpy.asarray(out, dtype=y.dtype)

gemv_no_inplace = Gemv(inplace=False)
gemv_inplace = Gemv(inplace=True)
# For the user interface. Opt will make them inplace later
gemv = gemv_no_inplace

class Ger(Op):
    """
    BLAS defines general rank-1 update GER as A <- A + alpha x y'

    for matrix A, scalar alpha, vectors x and y.

    This interface to GER allows non-destructive operation on A via the
    `destructive`
    argument to the constructor.

    :TODO: Create better classes ScipyGer and CGer that inherit from this class
    and override the make_thunk() method to use Scipy and C respectively.
    """
    def __init__(self, destructive):
        self.destructive = destructive
        if destructive:
            self.destroy_map = {0: [0]}

    def __eq__(self, other):
        return (type(self) == type(other) and
                self.destructive == other.destructive)

    def __hash__(self):
        return hash(type(self)) ^ hash(self.destructive)

    def __str__(self):
        if self.destructive:
            return '%s{destructive}' % self.__class__.__name__
        else:
            return '%s{non-destructive}' % self.__class__.__name__

    def make_node(self, A, alpha, x, y):
        A = T.as_tensor_variable(A)
        y = T.as_tensor_variable(y)
        x = T.as_tensor_variable(x)
        alpha = T.as_tensor_variable(alpha)
        if len(set([A.dtype, alpha.dtype, x.dtype, y.dtype])) != 1:
            raise TypeError('ger requires matching dtypes',
                    (A.dtype, alpha.dtype, x.dtype, y.dtype))
        if alpha.ndim != 0:
            raise TypeError('ger requires scalar alpha', alpha.type)
        if A.ndim != 2:
            raise TypeError('ger requires matrix for A', A.type)
        if x.ndim != 1:
            raise TypeError('ger requires vector for x', x.type)
        if y.ndim != 1:
            raise TypeError('ger requires vector for y', y.type)

        if x.dtype not in ('float32', 'float64', 'complex64', 'complex128'):
            raise TypeError('only float and complex types supported', x.dtype)
        return Apply(self, [A, alpha, x, y], [A.type()])

    def perform(self, node, inp, out):
        cA, calpha, cx, cy = inp
        cZ, = out
        if self.destructive:
            A = cA
        else:
            A = cA.copy()
        if calpha != 1:
            A += calpha * numpy.outer(cx, cy)
        else:
            A += numpy.outer(cx, cy)
        cZ[0] = A


ger = Ger(destructive=False)
ger_destructive = Ger(destructive=True)


def default_blas_ldflags():
    try:
        # If we are in a EPD installation, mkl is available
        blas_info = numpy.distutils.__config__.blas_opt_info
        if "EPD" in sys.version:
            use_unix_epd = True
            if sys.platform == 'win32':
                return ' '.join(
                    ['-L%s' % os.path.join(sys.prefix, "Scripts")] +
                    # Why on Windows, the library used are not the
                    # same as what is in
                    # blas_info['libraries']?
                    ['-l%s' % l for l in ["mk2_core", "mk2_intel_thread",
                                          "mk2_rt"]])
            elif sys.platform == 'darwin':
                # The env variable is needed to link with mkl
                new_path = os.path.join(sys.prefix, "lib")
                v = os.getenv("DYLD_FALLBACK_LIBRARY_PATH", None)
                if v is not None:
                    # Explicit version could be replaced by a symbolic
                    # link called 'Current' created by EPD installer
                    # This will resolve symbolic links
                    v = os.path.realpath(v)

                # The python __import__ don't seam to take into account
                # the new env variable "DYLD_FALLBACK_LIBRARY_PATH"
                # when we set with os.environ['...'] = X or os.putenv()
                # So we warn the user and tell him what todo.
                if v is None or new_path not in v.split(":"):
                    _logger.warning(
                        "The environment variable "
                        "'DYLD_FALLBACK_LIBRARY_PATH' does not contain "
                        "the '%s' path in its value. This will make "
                        "Theano use a slow version of BLAS. Update "
                        "'DYLD_FALLBACK_LIBRARY_PATH' to contain the "
                        "said value, this will disable this warning."
                        % new_path)


                    use_unix_epd = False
            if use_unix_epd:
                return ' '.join(
                    ['-L%s' % os.path.join(sys.prefix, "lib")] +
                    ['-l%s' % l for l in blas_info['libraries']])

        #if numpy was linked with library that are not installed, we
        #can't reuse them.
        if any(os.path.exists(dir) for dir in blas_info['library_dirs']):
            return ' '.join(
                        #TODO: the Gemm op below should separate the
                        # -L and -l arguments into the two callbacks
                        # that CLinker uses for that stuff.  for now,
                        # we just pass the whole ldflags as the -l
                        # options part.
                        ['-L%s' % l for l in blas_info['library_dirs']] +
                        ['-l%s' % l for l in blas_info['libraries']] +
                        [])
#                       ['-I%s' % l for l in blas_info['include_dirs']])
    except KeyError:
        pass

    # Even if we could not detect what was used for numpy, or if these
    # libraries are not found, most Linux systems have a libblas.so
    # readily available. We try to see if that's the case, rather
    # than disable blas.
    if GCC_compiler.try_flags(["-lblas"]):
        return "-lblas"
    else:
        return ""


AddConfigVar('blas.ldflags',
        "lib[s] to include for [Fortran] level-3 blas implementation",
        StrParam(default_blas_ldflags))


@utils.memoize
def ldflags(libs=True, flags=False, libs_dir=False, include_dir=False):
    """Return a list of libraries against which an Op's object file should be
    linked to benefit from a BLAS implementation.

    Default: ['blas'], but configuration variable config.blas.ldflags
    overrides this.
    """
    rval = []
    if libs_dir:
        found_dyn = False
        dirs = [x[2:] for x in config.blas.ldflags.split()
                if x.startswith('-L')]
        l = ldflags()
        for d in dirs:
            for f in os.listdir(d):
                if (f.endswith('.so') or f.endswith('.dylib') or
                    f.endswith('.dll')):
                    if any([f.find(ll) >= 0 for ll in l]):
                        found_dyn = True
        if not found_dyn and dirs:
            _logger.warning("We did not found a dynamic library into the "
                    "library_dir of the library we use for blas. If you use "
                    "ATLAS, make sure to compile it with dynamics library.")

    for t in config.blas.ldflags.split():
        #Remove extra quote.
        if t.startswith("'") or t.startswith('"'):
            t = t[1:]
        if t.endswith("'") or t.endswith('"'):
            t = t[:-1]

        try:
            t0, t1, t2 = t[0:3]
            assert t0 == '-'
        except Exception:
            raise ValueError('invalid token in config.blas.ldflags', t)
        if libs_dir and t1 == 'L':
            rval.append(t[2:])
        elif include_dir and t1 == 'I':
            raise ValueError('Include dirs are not used for blas. We disable'
                             ' this as this can hide other headers and this'
                             ' is not wanted.', t)
            rval.append(t[2:])
        elif libs and t1 == 'l':  # example -lmkl
            rval.append(t[2:])
        elif flags and t1 not in ['L', 'I', 'l']:  # example -openmp
            rval.append(t)
        elif flags and t1 == 'L':
            #to find it when we load the compiled op if the env of the
            #used is not well configured.
            rval.append('-Wl,-rpath,' + t[2:])
    return rval


class GemmRelated(Op):
    """Base class for Gemm and Dot22

    This class provides a kind of templated gemm Op.
    """
    def __eq__(self, other):
        return (type(self) == type(other))

    def __hash__(self):
        return hash(type(self))

    def __str__(self):
        return self.__class__.__name__

    def c_support_code(self):
        #return cblas_header_text()
        mod_str = """
        #ifndef MOD
        #define MOD %
        #endif
        static double time_time() // a time function like time.time()
        {
            struct timeval tv;
            gettimeofday(&tv, 0);
            return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
        }
        """
        return blas_header_text() + mod_str

    def c_headers(self):
        # std.cout doesn't require the '%' symbol to print stuff...
        # so it works much better with python's string-substitution stuff.
        return ['<iostream>', '<time.h>', '<sys/time.h>']

    def c_libraries(self):
        return ldflags()

    # code_cache_version is built by subclasses from
    #  build_gemm_version

    def c_compile_args(self):
        return ldflags(libs=False, flags=True)

    def c_lib_dirs(self):
        return ldflags(libs=False, libs_dir=True)

    def c_header_dirs(self):
        return ldflags(libs=False, include_dir=True)

    declare_NS = """
        int unit = 0;

        int type_num = PyArray_DESCR(%(_x)s)->type_num;
        int type_size = PyArray_DESCR(%(_x)s)->elsize; // in bytes

        npy_intp* Nx = PyArray_DIMS(%(_x)s);
        npy_intp* Ny = PyArray_DIMS(%(_y)s);
        npy_intp* Nz = 0; //PyArray_DIMS(%(_zout)s);

        npy_intp* Sx = PyArray_STRIDES(%(_x)s);
        npy_intp* Sy = PyArray_STRIDES(%(_y)s);
        npy_intp* Sz = 0; //PyArray_STRIDES(%(_zout)s);

        //strides for x, y, z in dimensions 0, 1
        int sx_0, sx_1, sy_0, sy_1, sz_0, sz_1;
        """

    #setup_z_Nz_Sz = None

    check_xyz_rank2 = """
        if (PyArray_NDIM(%(_x)s) != 2) {
            PyErr_Format(PyExc_NotImplementedError,
                         "rank(x) != 2. rank(x) is %%d.",
                         PyArray_NDIM(%(_x)s));
            %(fail)s;
        }
        if (PyArray_NDIM(%(_y)s) != 2) {
            PyErr_Format(PyExc_NotImplementedError,
                         "rank(y) != 2. rank(y) is %%d.", PyArray_NDIM(%(_y)s));
            %(fail)s;
        }
        if (%(_zout)s && PyArray_NDIM(%(_zout)s) != 2) {
            PyErr_Format(PyExc_NotImplementedError,
                         "rank(z) != 2. rank(z) is %%d.", PyArray_NDIM(%(_zout)s));
            %(fail)s;
        }
        """
    check_xyz_double_or_float = """
        if ((PyArray_DESCR(%(_x)s)->type_num != NPY_DOUBLE)
            && (PyArray_DESCR(%(_x)s)->type_num != NPY_FLOAT))
        {PyErr_SetString(PyExc_NotImplementedError, "type(x) is not double or float"); %(fail)s;}

        if ((PyArray_DESCR(%(_y)s)->type_num != NPY_DOUBLE)
            && (PyArray_DESCR(%(_y)s)->type_num != NPY_FLOAT))
        {PyErr_SetString(PyExc_NotImplementedError, "type(y) is not double or float"); %(fail)s;}

        if ((PyArray_DESCR(%(_zout)s)->type_num != NPY_DOUBLE)
            && (PyArray_DESCR(%(_zout)s)->type_num != NPY_FLOAT))
        {PyErr_SetString(PyExc_NotImplementedError, "type(z) is not double or float"); %(fail)s;}

        if ((PyArray_DESCR(%(_x)s)->type_num != PyArray_DESCR(%(_y)s)->type_num)
            ||(PyArray_DESCR(%(_x)s)->type_num != PyArray_DESCR(%(_zout)s)->type_num))
        { PyErr_SetString(PyExc_NotImplementedError, "type(x), type(y), type(z) are not all the same"); %(fail)s; }
        """

    #it is not necessary that a or b have the same type as x,y,z
    check_ab_double_or_float = """
        if ((PyArray_DESCR(%(_a)s)->type_num != NPY_DOUBLE)
            && (PyArray_DESCR(%(_a)s)->type_num != NPY_FLOAT))
        {PyErr_SetString(PyExc_NotImplementedError, "type(a) is not double or float"); %(fail)s;}

        if ((PyArray_DESCR(%(_b)s)->type_num != NPY_DOUBLE)
            && (PyArray_DESCR(%(_b)s)->type_num != NPY_FLOAT))
        {PyErr_SetString(PyExc_NotImplementedError, "type(b) is not double or float"); %(fail)s;}
        """

    check_dims = """
        if (Nx[0] != Nz[0])
        {
            PyErr_Format(PyExc_ValueError,
                "Shape mismatch: x has %%ld rows but z has %%ld rows",
                (long int)Nx[0], (long int)Nz[0]);
            %(fail)s;
        }
        if (Nx[1] != Ny[0])
        {
            PyErr_Format(PyExc_ValueError,
                "Shape mismatch: x has %%ld cols (and %%ld rows) but y has %%ld rows (and %%ld cols)",
                (long int)Nx[1], (long int)Nx[0], (long int)Ny[0], (long int)Ny[1]);
            %(fail)s;
        }
        if (Ny[1] != Nz[1])
        {
            PyErr_Format(PyExc_ValueError,
                "Shape mismatch: y has %%ld cols but z has %%ld cols",
                (long int)Ny[1], (long int)Nz[1]);
            %(fail)s;
        }

        // We must not raise an error when Nx[1] == 0. This would disable cases
        // that numpy.dot accept.
        """

    check_strides = """
        /*
        If some matrices are not contiguous on either dimensions,
        or have invalid strides, copy their content into a contiguous one
        */
        if ((Sx[0] < 1) || (Sx[1] < 1) || (Sx[0] MOD type_size) || (Sx[1] MOD type_size)
            || ((Sx[0] != type_size) && (Sx[1] != type_size)))
        {
            PyArrayObject * _x_copy = (PyArrayObject *) PyArray_Copy(%(_x)s);
            if (!_x_copy)
                %(fail)s
            Py_XDECREF(%(_x)s);
            %(_x)s = _x_copy;
            Sx = PyArray_STRIDES(%(_x)s);
        }

        if ((Sy[0] < 1) || (Sy[1] < 1) || (Sy[0] MOD type_size) || (Sy[1] MOD type_size)
            || ((Sy[0] != type_size) && (Sy[1] != type_size)))
        {
            PyArrayObject * _y_copy = (PyArrayObject *) PyArray_Copy(%(_y)s);
            if (!_y_copy)
                %(fail)s
            Py_XDECREF(%(_y)s);
            %(_y)s = _y_copy;
            Sy = PyArray_STRIDES(%(_y)s);
        }

        if ((Sz[0] < 1) || (Sz[1] < 1) || (Sz[0] MOD type_size) || (Sz[1] MOD type_size)
            || ((Sz[0] != type_size) && (Sz[1] != type_size)))
        {
            PyArrayObject * _z_copy = (PyArrayObject *) PyArray_Copy(%(_zout)s);
            if (!_z_copy)
                %(fail)s
            Py_XDECREF(%(_zout)s);
            %(_zout)s = _z_copy;
            Sz = PyArray_STRIDES(%(_zout)s);
        }
        """

    encode_strides_in_unit = """
        /*
        encode the stride structure of _x,_y,_zout into a single integer
        */
        unit |= ((Sx[1] == type_size) ? 0x0 : (Sx[0] == type_size) ? 0x1 : 0x2) << 8;
        unit |= ((Sy[1] == type_size) ? 0x0 : (Sy[0] == type_size) ? 0x1 : 0x2) << 4;
        unit |= ((Sz[1] == type_size) ? 0x0 : (Sz[0] == type_size) ? 0x1 : 0x2) << 0;
        """

    compute_strides = """
        /* create appropriate strides for malformed matrices that are row or column
         * vectors, or empty matrices.
         * In that case, the value of the stride does not really matter, but
         * some versions of BLAS insist that:
         *  - they are not smaller than the number of elements in the array,
         *  - they are not 0.
         */
        sx_0 = (Nx[0] > 1) ? Sx[0]/type_size : (Nx[1] + 1);
        sx_1 = (Nx[1] > 1) ? Sx[1]/type_size : (Nx[0] + 1);
        sy_0 = (Ny[0] > 1) ? Sy[0]/type_size : (Ny[1] + 1);
        sy_1 = (Ny[1] > 1) ? Sy[1]/type_size : (Ny[0] + 1);
        sz_0 = (Nz[0] > 1) ? Sz[0]/type_size : (Nz[1] + 1);
        sz_1 = (Nz[1] > 1) ? Sz[1]/type_size : (Nz[0] + 1);
        """

    begin_switch_typenum = """
        switch (type_num)
        {
        """

    case_float = """
            case NPY_FLOAT:
            {
        """

    #case_float_ab_constants = None

    case_float_gemm = """
                float* x = (float*)PyArray_DATA(%(_x)s);
                float* y = (float*)PyArray_DATA(%(_y)s);
                float* z = (float*)PyArray_DATA(%(_zout)s);
                char N = 'N';
                char T = 'T';
                int Nz0 = Nz[0], Nz1 = Nz[1], Nx1 = Nx[1];
                //std::cerr << (unit/256) MOD 16 << (unit / 16) MOD 16 << unit MOD 16<< '\\n';
                //double t0 = time_time();
                switch(unit)
                {
                    case 0x000: sgemm_(&N, &N, &Nz1, &Nz0, &Nx1, &a, y, &sy_0, x, &sx_0, &b, z, &sz_0); break;
                    case 0x100: sgemm_(&N, &T, &Nz1, &Nz0, &Nx1, &a, y, &sy_0, x, &sx_1, &b, z, &sz_0); break;
                    case 0x010: sgemm_(&T, &N, &Nz1, &Nz0, &Nx1, &a, y, &sy_1, x, &sx_0, &b, z, &sz_0); break;
                    case 0x110: sgemm_(&T, &T, &Nz1, &Nz0, &Nx1, &a, y, &sy_1, x, &sx_1, &b, z, &sz_0); break;
                    case 0x001: sgemm_(&T, &T, &Nz0, &Nz1, &Nx1, &a, x, &sx_0, y, &sy_0, &b, z, &sz_1); break;
                    case 0x101: sgemm_(&N, &T, &Nz0, &Nz1, &Nx1, &a, x, &sx_1, y, &sy_0, &b, z, &sz_1); break;
                    case 0x011: sgemm_(&T, &N, &Nz0, &Nz1, &Nx1, &a, x, &sx_0, y, &sy_1, &b, z, &sz_1); break;
                    case 0x111: sgemm_(&N, &N, &Nz0, &Nz1, &Nx1, &a, x, &sx_1, y, &sy_1, &b, z, &sz_1); break;
                    default: PyErr_SetString(PyExc_ValueError, "some matrix has no unit stride"); %(fail)s;
                };
                //fprintf(stderr, "Calling sgemm %%i %%i %%i %%i took %%f\\n", unit, Nz1, Nz0, Nx1, time_time() - t0);
        """

    case_double = """
            }
            break;
            case NPY_DOUBLE:
            {
        """

    #case_double_ab_constants = None

    case_double_gemm = """
                double* x = (double*)PyArray_DATA(%(_x)s);
                double* y = (double*)PyArray_DATA(%(_y)s);
                double* z = (double*)PyArray_DATA(%(_zout)s);
                char N = 'N';
                char T = 'T';
                int Nz0 = Nz[0], Nz1 = Nz[1], Nx1 = Nx[1];
                //std::cerr << (unit/256) MOD 16 << (unit / 16) MOD 16 << unit MOD 16<< '\\n';
                //double t0 = time_time();
                //fprintf(stderr, "unit=%%x N= %%i %%i %%i S = %%i %%i %%i %%i %%i %%i\\n", unit,
                //Nz1, Nz0, Nx1,
                //sy_0, sy_1,
                //sx_0, sx_1,
                //sz_0, sz_1
                //);
                switch(unit)
                {
                    case 0x000: dgemm_(&N, &N, &Nz1, &Nz0, &Nx1, &a, y, &sy_0, x, &sx_0, &b, z, &sz_0); break;
                    case 0x100: dgemm_(&N, &T, &Nz1, &Nz0, &Nx1, &a, y, &sy_0, x, &sx_1, &b, z, &sz_0); break;
                    case 0x010: dgemm_(&T, &N, &Nz1, &Nz0, &Nx1, &a, y, &sy_1, x, &sx_0, &b, z, &sz_0); break;
                    case 0x110: dgemm_(&T, &T, &Nz1, &Nz0, &Nx1, &a, y, &sy_1, x, &sx_1, &b, z, &sz_0); break;
                    case 0x001: dgemm_(&T, &T, &Nz0, &Nz1, &Nx1, &a, x, &sx_0, y, &sy_0, &b, z, &sz_1); break;
                    case 0x101: dgemm_(&N, &T, &Nz0, &Nz1, &Nx1, &a, x, &sx_1, y, &sy_0, &b, z, &sz_1); break;
                    case 0x011: dgemm_(&T, &N, &Nz0, &Nz1, &Nx1, &a, x, &sx_0, y, &sy_1, &b, z, &sz_1); break;
                    case 0x111: dgemm_(&N, &N, &Nz0, &Nz1, &Nx1, &a, x, &sx_1, y, &sy_1, &b, z, &sz_1); break;
                    default: PyErr_SetString(PyExc_ValueError, "some matrix has no unit stride"); %(fail)s;
                };
                //fprintf(stderr, "Calling dgemm %%i %%i %%i %%i took %%f\\n", unit, Nz1, Nz0, Nx1, time_time()- t0);
        """

    end_switch_typenum = """
            }
            break;
        }
        """

    def build_gemm_call(self):

        return reduce(str.__add__, (
            self.declare_NS,
            self.check_xyz_rank2,
            self.setup_z_Nz_Sz,
            self.check_xyz_double_or_float,
            self.check_ab_double_or_float,
            self.check_dims,
            self.check_strides,
            self.encode_strides_in_unit,
            self.compute_strides,
            self.begin_switch_typenum,
            self.case_float,
            self.case_float_ab_constants,
            self.case_float_gemm,
            self.case_double,
            self.case_double_ab_constants,
            self.case_double_gemm,
            self.end_switch_typenum), '')

    def build_gemm_version(self):
        return (12, blas_header_version())


class Gemm(GemmRelated):
    """In-place version of matrix-matrix multiplication (with accumulation):

    When a and b are scalars and x, y, and z are matrices, then

        gemm(z,a,x,y,b)

    is similar to

        b*z + a*dot(x,y)

    The difference between the two is that the top form is destructive
    on z, whereas the bottom form is not.  Gemm works in-place on the
    storage associated with z, and the L{Variable} returned by Gemm
    has a storage that will be aliased to the storage of the z
    argument. Because of this in-place computation, an L{Apply} of
    this op will destroy the L{Variable} z on which it operates.  (See
    L{DestructiveOps} for an explanation of what destroying means in
    the context of theano graphs. See L{BlasLapackSupport} for more
    optimized linear algebra operations.)

    """
    E_rank = 'gemm only works for rank 2'
    E_scalar = 'gemm requires scalar argument'
    E_z_uniq = 'argument z aliased to x or y'  # TODO: justify / delete this
    E_mixed = 'gemm requires matching dtypes'
    E_float = 'gemm requires floating-point dtypes'

    def __init__(self, inplace):
        self.__setstate__({'inplace': inplace})

    def __eq__(self, other):
        return (type(self) == type(other) and
                self.inplace == other.inplace)

    def __hash__(self):
        return hash(type(self)) ^ hash(self.inplace)

    def __str__(self):
        if self.inplace:
            inplace_str = 'inplace'
        else:
            inplace_str = 'no_inplace'
        return '%s{%s}' % (self.__class__.__name__, inplace_str)

    def __setstate__(self, dct):
        inplace = dct.get('inplace', True)
        if inplace:
            self.destroy_map = {0: [0]}
            self.setup_z_Nz_Sz = self.setup_z_Nz_Sz_inplace
        else:
            self.setup_z_Nz_Sz = self.setup_z_Nz_Sz_outplace
        self.inplace = inplace

    def __getstate__(self):
        return dict(inplace=self.inplace)

    def make_node(self, *inputs):
        inputs = map(T.as_tensor_variable, inputs)
        if len(inputs) != 5:
            raise TypeError(
                "Wrong number of inputs for %s (expected 5, got %s)" %
                (self, len(inputs)))
        z, a, x, y, b = inputs
        zr, xr, yr = [set(view_roots(i)) for i in z, x, y]

        # TODO: justify / delete
        if zr.intersection(xr):
            raise InconsistencyError(Gemm.E_z_uniq, (z, x))
        if zr.intersection(yr):
            raise InconsistencyError(Gemm.E_z_uniq, (z, y))

        if z.ndim != 2:
            raise TypeError(Gemm.E_rank, z)
        if a.ndim != 0:
            raise TypeError(Gemm.E_scalar, a)
        if x.ndim != 2:
            raise TypeError(Gemm.E_rank, x)
        if y.ndim != 2:
            raise TypeError(Gemm.E_rank, y)
        if b.ndim != 0:
            raise TypeError(Gemm.E_scalar, b)

        if not (z.dtype == a.dtype == x.dtype == y.dtype == b.dtype):
            raise TypeError(Gemm.E_mixed,
                    (z.dtype, a.dtype, x.dtype, y.dtype, b.dtype))

        if (not z.dtype.startswith('float')
                and not z.dtype.startswith('complex')):
            raise TypeError(Gemm.E_float, (z.dtype))

        output = z.type()
        return Apply(self, inputs, [output])

    def perform(self, node, inp, out):
        z, a, x, y, b = inp
        zout, = out
        assert a.shape == ()
        assert b.shape == ()
        if not self.inplace:
            z = z.copy()  # the original z will not be changed
        if z.shape == ():
            z.itemset(z * a + b * numpy.dot(x, y))
            zout[0] = z
        else:
            if b == 0.0:
                if a == 1.0:
                    z[:] = numpy.dot(x, y)
                elif a == -1.0:
                    z[:] = -numpy.dot(x, y)
                else:
                    z[:] = a * numpy.dot(x, y)
            elif b == 1.0:
                if a == 1.0:
                    z += numpy.dot(x, y)
                elif a == -1.0:
                    z -= numpy.dot(x, y)
                else:
                    z += a * numpy.dot(x, y)
            else:
                z *= b
                z += a * numpy.dot(x, y)
            zout[0] = z

    setup_z_Nz_Sz_inplace = """
        if (%(_zout)s != %(_z)s)
        {
            if (%(_zout)s)
            {
                Py_DECREF(%(_zout)s);
            }
            %(_zout)s = %(_z)s;
            Py_INCREF(%(_zout)s);
        }
        Nz = PyArray_DIMS(%(_z)s);
        Sz = PyArray_STRIDES(%(_z)s);
        """

    setup_z_Nz_Sz_outplace = """
        if ((NULL == %(_zout)s)
            || (PyArray_DIMS(%(_zout)s)[0] != PyArray_DIMS(%(_z)s)[0])
            || (PyArray_DIMS(%(_zout)s)[1] != PyArray_DIMS(%(_z)s)[1])
            || (PyArray_STRIDES(%(_zout)s)[0] <= 0)
            || (PyArray_STRIDES(%(_zout)s)[1] <= 0)
            || (PyArray_STRIDES(%(_zout)s)[0] MOD type_size)
            || (PyArray_STRIDES(%(_zout)s)[1] MOD type_size)
            || ((PyArray_STRIDES(%(_zout)s)[0] != type_size)
                && (PyArray_STRIDES(%(_zout)s)[1] != type_size)))
        {
            Py_XDECREF(%(_zout)s);
            npy_intp dims[2];
            dims[0] = PyArray_DIMS(%(_z)s)[0];
            dims[1] = PyArray_DIMS(%(_z)s)[1];
            %(_zout)s = (PyArrayObject*)PyArray_SimpleNew(2, dims,
                                                          type_num_%(_z)s);
            //fprintf(stderr, "Gemm Allocating %%i %%i\\n", dims[0], dims[1]);
            if(!%(_zout)s) {
                PyErr_SetString(PyExc_MemoryError,
                                "failed to alloc gemm_no_inplace output");
                %(fail)s
            }
        }
        Nz = PyArray_DIMS(%(_zout)s);
        Sz = PyArray_STRIDES(%(_zout)s);

        if (PyArray_DESCR(%(_zout)s)->type_num == NPY_FLOAT)
        {
            float * zoutdata = (float*)PyArray_DATA(%(_zout)s);
            int zoi = Sz[0] / sizeof(float);
            int zoj = Sz[1] / sizeof(float);
            const float * zdata = (float*)PyArray_DATA(%(_z)s);
            int zi = PyArray_STRIDES(%(_z)s)[0]/sizeof(float);
            int zj = PyArray_STRIDES(%(_z)s)[1]/sizeof(float);
            for (int i = 0; i < Nz[0]; ++i)
            {
                for (int j = 0; j < Nz[1]; ++j)
                {
                    zoutdata[zoi*i + zoj*j] = zdata[zi*i + zj*j];
                }
            }
        }
        else if (PyArray_DESCR(%(_zout)s)->type_num == NPY_DOUBLE)
        {
            double * zoutdata = (double*) PyArray_DATA(%(_zout)s);
            int zoi = Sz[0] / sizeof(double);
            int zoj = Sz[1] / sizeof(double);
            const double * zdata = (double*)PyArray_DATA(%(_z)s);
            int zi = PyArray_STRIDES(%(_z)s)[0]/sizeof(double);
            int zj = PyArray_STRIDES(%(_z)s)[1]/sizeof(double);
            for (int i = 0; i < Nz[0]; ++i)
            {
                for (int j = 0; j < Nz[1]; ++j)
                {
                    zoutdata[zoi*i + zoj*j] = zdata[zi*i + zj*j];
                }
            }
        }
        else
        {
            PyErr_SetString(PyExc_AssertionError,
                            "neither float nor double dtype");
            %(fail)s
        }
        """

    case_float_ab_constants = """
        #define REAL float
        float a = (PyArray_DESCR(%(_a)s)->type_num == NPY_FLOAT)
        ? (REAL)(((float*)PyArray_DATA(%(_a)s))[0])
        : (REAL)(((double*)PyArray_DATA(%(_a)s))[0]);
        float b = (PyArray_DESCR(%(_b)s)->type_num == NPY_FLOAT) ?
        (REAL)(((float*)PyArray_DATA(%(_b)s))[0])
        : (REAL)(((double*)PyArray_DATA(%(_b)s))[0]);
        #undef REAL
        """
    case_double_ab_constants = """
        #define REAL double
        double a = (PyArray_DESCR(%(_a)s)->type_num == NPY_FLOAT)
        ? (REAL)(((float*)PyArray_DATA(%(_a)s))[0])
        : (REAL)(((double*)PyArray_DATA(%(_a)s))[0]);
        double b = (PyArray_DESCR(%(_b)s)->type_num == NPY_FLOAT) ?
        (REAL)(((float*)PyArray_DATA(%(_b)s))[0])
        : (REAL)(((double*)PyArray_DATA(%(_b)s))[0]);
        #undef REAL
        """

    def c_code(self, node, name, inp, out, sub):
        _z, _a, _x, _y, _b = inp
        _zout, = out
        if node.inputs[0].type.dtype.startswith('complex'):
            raise utils.MethodNotDefined('%s.c_code' \
                    % self.__class__.__name__)
        if not config.blas.ldflags:
            return super(Gemm, self).c_code(node, name,
                                            (_z, _a, _x, _y, _b), (_zout, ),
                                            sub)
        full_code = self.build_gemm_call() % dict(locals(), **sub)
        return full_code

    def c_code_cache_version(self):
        gv = self.build_gemm_version()
        if gv:
            return (4,) + gv
        else:
            return gv

gemm_inplace = Gemm(inplace=True)
gemm_no_inplace = Gemm(inplace=False)
# For the user interface. Theano optimization will make them inplace
gemm = gemm_no_inplace
pprint.assign(gemm_inplace, FunctionPrinter('gemm_inplace'))
pprint.assign(gemm_no_inplace, FunctionPrinter('gemm_no_inplace'))


def res_is_a(node, op, maxclients=None):
    if maxclients is not None:
        retval = (len(node.clients) <= maxclients)
    else:
        retval = True

    return node.owner \
              and node.owner.op == op \
              and retval


def _as_scalar(res, dtype=None):
    """Return None or a TensorVariable whose type is in T.float_scalar_types"""
    if dtype is None:
        dtype = config.floatX
    if numpy.all(res.type.broadcastable):
        while res.owner and isinstance(res.owner.op, T.DimShuffle):
            res = res.owner.inputs[0]
        # may still have some number of True's
        if res.type.broadcastable:
            rval = res.dimshuffle()
        else:
            rval = res
        if rval.type.dtype[:3] in ('int', 'uin'):
            # We check that the upcast of res and dtype won't change dtype.
            # If dtype is float64, we will cast int64 to float64.
            # This is valid when res is a scalar used as input to a dot22
            # as the cast of the scalar can be done before or after the dot22
            # and this will give the same result.
            if theano.scalar.upcast(res.dtype, dtype) == dtype:
                return T.cast(rval, dtype)
            else:
                return None

        return rval


def _is_real_matrix(res):
    return res.type.dtype in ('float32', 'float64') \
            and res.type.ndim == 2 \
            and res.type.broadcastable[0] == False \
            and res.type.broadcastable[1] == False  # cope with tuple vs. list


def _is_real_vector(res):
    return res.type.dtype in ('float32', 'float64') \
            and res.type.ndim == 1 \
            and res.type.broadcastable[0] == False


def _beta_L_plus_alpha_M(beta, L, alpha, M, recurse_flip=True):
    #print 'BETA L + ALPHA M', beta, L, alpha, M, recurse_flip
    #EXPRESSION: (beta * L) + (alpha * M)

    # we've already checked the client counts, now just make the type check.
    ####if res_is_a(M, _dot22, 1):
    if M.owner and M.owner.op == _dot22:
        Ml, Mr = M.owner.inputs
        rval = [gemm_no_inplace(L, alpha, Ml, Mr, beta)]
        #print 'GEMM 0', rval, beta, L, alpha, M
        return rval, M

    # it also might be the case that there is a dimshuffle between the +
    # and the dot22. local_dot_to_dot22 in particular will put in such things.
    if M.owner and isinstance(M.owner.op, T.DimShuffle):
        MM = M.owner.inputs[0]
        if tuple(M.owner.op.new_order) == (0,):
            # it is making a column MM into a vector
            if MM.owner and MM.owner.op == _dot22:
                MMl, MMr = MM.owner.inputs
                g = gemm_no_inplace(L.dimshuffle(0, 'x'),
                        alpha, MMl, MMr, beta)
                rval = [g.dimshuffle(0)]
                return rval, MM
        if tuple(M.owner.op.new_order) == (1,):
            # it is making a row MM into a vector
            if MM.owner and MM.owner.op == _dot22:
                MMl, MMr = MM.owner.inputs
                g = gemm_no_inplace(L.dimshuffle('x', 0),
                        alpha, MMl, MMr, beta)
                rval = [g.dimshuffle(1)]
                return rval, MM
        if tuple(M.owner.op.new_order) == ():
            # it is making a row MM into a vector
            if MM.owner and MM.owner.op == _dot22:
                MMl, MMr = MM.owner.inputs
                g = gemm_no_inplace(L.dimshuffle('x', 'x'),
                        alpha, MMl, MMr, beta)
                rval = [g.dimshuffle()]
                return rval, MM

    # this is False'd out because of inadequate testing.
    # TODO see ticket #237
    if False and res_is_a(M, gemm_no_inplace, 1):
        #EXPRESSION: (beta * L) + (alpha * (gemm_no_inplace(G, a, u, v, b)))
        #EXPRESSION: (beta * L) + alpha * (b * G) + alpha * a * dot(u, v)
        G, a, u, v, b = M.owner.inputs
        #print 'GEMM', G, L

        if res_is_a(G, _dot22, 1):
            #EXPRESSION: (beta * L) +
            #            (alpha * (gemm_no_inplace(dot(x,y), a, u, v, b)))
            x, y = G.owner.inputs

            #EXPRESSION: (beta * L) + (alpha * ((b*dot(x,y) +
            #            (a * dot(u, v)))))
            #EXPRESSION: (beta * L) + (alpha*b*dot(x,y)) +
            #            (alpha * a * dot(u, v))
            rval = [gemm_no_inplace(gemm_no_inplace(L, alpha * b, x, y, beta),
                                    alpha * a, u, v, 1.0)]
            return rval
        if (G is L):
            #EXPRESSION: (beta * L) + (alpha*b*L) + (alpha * a * dot(u, v))
            rval = [gemm_no_inplace(L, alpha * a, u, v, alpha * b + beta)]
            return rval
        if (1.0 != alpha):
            #at the very least, move the alpha inside the gemm_no_inplace
            rval = [beta * L + gemm_no_inplace(G, alpha * a, u, v, alpha * b)]
            return rval

    if recurse_flip:
        return _beta_L_plus_alpha_M(alpha, M, beta, L, recurse_flip=False)
    else:
        return False, False


def _gemm_canonicalize(r, scale, rval, maxclients):
    # Tries to interpret node as a sum of scalars * (vectors or matrices)
    def scaled(thing):
        if scale == 1:
            return thing
        if scale == -1:
            return -thing
        else:
            return scale * thing
    try:
        r.type.broadcastable
    except Exception:
        return None

    if ((r.type.ndim not in (1, 2)) or
            r.type.dtype not in ('float32', 'float64',
                                 'complex64', 'complex128')):
        rval.append(scaled(r))
        return rval

    if maxclients and len(getattr(r, 'clients', [])) > maxclients:
        rval.append((scale, r))
        return rval

    if r.owner and r.owner.op == T.sub:
        _gemm_canonicalize(r.owner.inputs[0], scale, rval, 1)
        _gemm_canonicalize(r.owner.inputs[1], -scale, rval, 1)

    elif r.owner and r.owner.op == T.add:
        for i in r.owner.inputs:
            _gemm_canonicalize(i, scale, rval, 1)

    elif r.owner and r.owner.op == T.neg:
        _gemm_canonicalize(r.owner.inputs[0], -scale, rval, 1)

    elif r.owner and r.owner.op == T.mul:
        scalars = []
        vectors = []
        matrices = []
        for i in r.owner.inputs:
            if numpy.all(i.type.broadcastable):
                while i.owner and isinstance(i.owner.op, T.DimShuffle):
                    i = i.owner.inputs[0]
                if i.type.broadcastable:
                    scalars.append(i.dimshuffle())
                else:
                    scalars.append(i)
            elif _is_real_vector(i):
                vectors.append(i)
            elif _is_real_matrix(i):
                matrices.append(i)
            else:
                # just put the original arguments as in the base case
                rval.append((scale, r))
                return rval
        if len(matrices) == 1:
            assert len(vectors) == 0
            m = matrices[0]
            if len(scalars) == 0:
                _gemm_canonicalize(m, scale, rval, 1)
            elif len(scalars) == 1:
                _gemm_canonicalize(m, scaled(scalars[0]), rval, 1)
            else:
                _gemm_canonicalize(m, T.mul(scaled(scalars[0]), *scalars[1:]),
                                   rval, 1)
        elif len(vectors) == 1:
            assert len(matrices) == 0
            v = vectors[0]
            if len(scalars) == 0:
                _gemm_canonicalize(v, scale, rval, 1)
            elif len(scalars) == 1:
                _gemm_canonicalize(v, scaled(scalars[0]), rval, 1)
            else:
                _gemm_canonicalize(v, T.mul(scaled(scalars[0]),
                                            *scalars[1:]), rval, 1)
        else:  # lets not open this up
            rval.append((scale, r))
    else:
        rval.append((scale, r))
    return rval


def _factor_canonicalized(lst):
    # remove duplicates from canonicalized list

    # we only delete out of the right end of the list,
    # once i has touched a list element, it is permantent
    lst = list(lst)
    #print 'FACTOR', lst
    #for t in lst:
    #    if not isinstance(t, (list, tuple)):
    #        t = (t,)
    #    for e in t:
    #        try:
    #            theano.printing.debugprint(e)
    #        except TypeError:
    #            print e, type(e)
    i = 0
    while i < len(lst) - 1:
        try:
            s_i, M_i = lst[i]
        except Exception:
            i += 1
            continue

        j = i + 1
        while j < len(lst):
            try:
                s_j, M_j = lst[j]
            except Exception:
                j += 1
                continue

            if M_i is M_j:
                s_i = s_i + s_j
                lst[i] = (s_i, M_i)
                del lst[j]
            else:
                j += 1
        i += 1
    return lst


def _gemm_from_factored_list(lst):
    """Returns None, or a list to replace node.outputs
    """

    # Make every pair in list have matching dtypes
    # sM can be a tuple of 2 elements or a theano variable.
    # We should not use __len__ as theano variables don't support
    # it. I don't want to change this to isinstance(sM, tuple)
    # as I'm not able to make a test that triggers this case.
    def is_pair(sM):
        try:
            s, M = sM
            return True
        except Exception:
            return False

    lst2 = []
    # Remove the tuple that can't be cast correctly.
    # This can happen when we try to cast a complex to a real
    for sM in lst:
        if is_pair(sM):
            sm0, sm1 = sM
            sm0 = T.as_tensor_variable(sm0)
            if theano.scalar.upcast(sm0.dtype, sm1.dtype) == sm1.dtype:
                lst2.append((T.cast(sm0, sm1.dtype), sM[1]))
    lst = lst2

    # Try every pair in the sM_list, trying to turn it into a gemm operation
    for i in xrange(len(lst) - 1):
        s_i, M_i = lst[i]

        for j in xrange(i + 1, len(lst)):
            s_j, M_j = lst[j]

            if M_i.type != M_j.type:
                continue

            #print 'TRYING', (s_i, M_i, s_j, M_j)

            gemm_of_sM_list, old_dot22 = _beta_L_plus_alpha_M(s_i, M_i,
                                                              s_j, M_j)
            #print 'GOT IT', gemm_of_sM_list
            if gemm_of_sM_list:
                def item_to_var(t):
                    try:
                        s, M = t
                    except Exception:
                        return t
                    if s == 1:
                        return M
                    if s == -1:
                        return -M
                    return s * M

                assert len(gemm_of_sM_list) == 1
                add_inputs = [item_to_var(input)
                        for k, input in enumerate(lst) if k not in (i, j)]
                add_inputs.extend(gemm_of_sM_list)
                if len(add_inputs) > 1:
                    rval = [T.add(*add_inputs)]
                else:
                    rval = add_inputs
                #print "RETURNING GEMM THIGN", rval
                return rval, old_dot22


def _gemm_from_node2(node):
    """
    :todo: In many expressions, there are many ways to turn it into a
        gemm.  For example dot(a,b) + c + d.  This function should
        return all of them, so that if one version of gemm causes a
        cycle in the graph, then another application of gemm can be
        tried.

    """
    lst = []
    t0 = time.time()
    _gemm_canonicalize(node.outputs[0], 1.0, lst, 0)
    t1 = time.time()

    #print "GEMM CANON", lst
    if len(lst) > 1:
        lst = _factor_canonicalized(lst)
        t2 = time.time()
        rval = _gemm_from_factored_list(lst)
        t3 = time.time()

        # It can happen that _factor_canonicalized and
        # _gemm_from_factored_list return a node with an incorrect
        # type.  This happens in particular when one of the scalar
        # factors forces the upcast of the whole expression.  In that
        # case, we simply skip that candidate for Gemm.  This was
        # discussed in
        # http://groups.google.com/group/theano-dev/browse_thread/thread/a3096c82856e3ad5,
        # but never made it into a trac ticket.

        if rval and (rval[0][0].type == node.outputs[0].type):
            return rval, t1 - t0, t2 - t1, t3 - t2

    return None, t1 - t0, 0, 0


class GemmOptimizer(Optimizer):
    """Graph optimizer for inserting Gemm operations"""
    def __init__(self):
        Optimizer.__init__(self)
        self.warned = False

    def add_requirements(self, fgraph):
        fgraph.attach_feature(toolbox.ReplaceValidate())
        fgraph.attach_feature(DestroyHandler())

    def apply(self, fgraph):
        did_something = True
        nb_iter = 0
        nb_replacement = 0
        nb_replacement_didn_t_remove = 0
        nb_inconsistency_make = 0
        nb_inconsistency_replace = 0
        time_canonicalize = 0
        time_factor_can = 0
        time_factor_list = 0
        time_toposort = 0
        while did_something:
            t0 = time.time()
            nodelist = list(fgraph.toposort())
            time_toposort += time.time() - t0
            did_something = False
            nodelist.reverse()
            for node in nodelist:
                if not (isinstance(node.op, T.Elemwise) and
                        isinstance(node.op.scalar_op,
                                   (theano.scalar.Add, theano.scalar.Sub,
                                    theano.scalar.Neg, theano.scalar.Mul))):
                    continue
                if not node in fgraph.apply_nodes:
                    # This mean that we already removed this node from
                    # the graph
                    continue
                try:
                    new_outputs, time1, time2, time3 = _gemm_from_node2(node)
                    time_canonicalize += time1
                    time_factor_can += time2
                    time_factor_list += time3
                except InconsistencyError, e:
                    nb_inconsistency_make += 1
                    continue
                if new_outputs:
                    new_outputs, old_dot22 = new_outputs
                    assert len(new_outputs) == len(node.outputs)
                    try:
                        fgraph.replace_all_validate_remove(
                            zip(node.outputs, new_outputs),
                            [old_dot22],
                            reason='GemmOptimizer',
                            #For now we disable the warning as we know case
                            #that we need to fix.
                            warn=False,  # warn=not self.warned
                        )
                        did_something = True
                        nb_replacement += 1
                    except InconsistencyError, e:
                        # TODO: retry other applications of gemm (see comment
                        # in _gemm_from_node)
                        nb_inconsistency_replace += 1
                    except ReplacementDidntRemovedError, e:
                        nb_replacement_didn_t_remove += 1
                        self.warned = True
            nb_iter += 1
        return (self, nb_iter, nb_replacement, nb_replacement_didn_t_remove,
                nb_inconsistency_make, nb_inconsistency_replace,
                time_canonicalize, time_factor_can,
                time_factor_list, time_toposort)

    @staticmethod
    def print_profile(stream, prof, level=0):
        blanc = ('    ' * level)
        #1946.912556s - ('gemm_optimizer', 'GemmOptimizer', 1)
        print >> stream, blanc, "GemmOptimizer"
        print >> stream, blanc, " nb_iter", prof[1]
        print >> stream, blanc, " nb_replacement", prof[2]
        print >> stream, blanc, " nb_replacement_didn_t_remove", prof[3]
        print >> stream, blanc, " nb_inconsistency_make", prof[4]
        print >> stream, blanc, " nb_inconsistency_replace", prof[5]
        print >> stream, blanc, " time_canonicalize", prof[6]
        print >> stream, blanc, " time_factor_can", prof[7]
        print >> stream, blanc, " time_factor_list", prof[8]
        print >> stream, blanc, " time_toposort", prof[9]


class Dot22(GemmRelated):
    """Compute a matrix-matrix product.
    This is a specialization of the more general Dot()
    """
    def make_node(self, x, y):
        dtypes = ('float32', 'float64', 'complex64', 'complex128')
        if x.type.ndim != 2 or x.type.dtype not in dtypes:
            raise TypeError(x)
        if y.type.ndim != 2 or y.type.dtype not in dtypes:
            raise TypeError(y)
        if y.type.dtype != x.type.dtype:
            raise TypeError('dtype mismatch to Dot22')
        bz = (x.type.broadcastable[0], y.type.broadcastable[1])
        outputs = [T.tensor(x.type.dtype, bz)]
        return Apply(self, [x, y], outputs)

    def perform(self, node, inp, out):
        x, y = inp
        z, = out
        try:
            z[0] = numpy.asarray(numpy.dot(x, y))
        except ValueError, e:
            # The error raised by numpy has no shape information, we mean to
            # add that
            e.args = e.args + (x.shape, y.shape)
            raise

    def __str__(self):
        return "_dot22"

    setup_z_Nz_Sz = """
        if ((NULL == %(_zout)s)
            || (PyArray_DIMS(%(_zout)s)[0] != PyArray_DIMS(%(_x)s)[0])
            || (PyArray_DIMS(%(_zout)s)[1] != PyArray_DIMS(%(_y)s)[1]))
        {
            if (NULL != %(_zout)s) Py_XDECREF(%(_zout)s);
            npy_intp dims[2];
            dims[0] = PyArray_DIMS(%(_x)s)[0];
            dims[1] = PyArray_DIMS(%(_y)s)[1];
            %(_zout)s = (PyArrayObject*)PyArray_SimpleNew(2, dims,
                            type_num_%(_x)s);
            //fprintf(stderr, "Dot Allocating %%i %%i\\n", dims[0], dims[1]);
            if(!%(_zout)s) {
                PyErr_SetString(PyExc_MemoryError,
                                "failed to alloc dot22 output");
                %(fail)s
            }
        }
        Nz = PyArray_DIMS(%(_zout)s);
        Sz = PyArray_STRIDES(%(_zout)s);

        """
    check_ab_double_or_float = ""
    case_float_ab_constants = """
                float a = 1.0;
                float b = 0.0;
        """
    case_double_ab_constants = """
                double a = 1.0;
                double b = 0.0;
        """

    def c_code(self, node, name, inp, out, sub):  # DEBUG
        _x, _y = inp
        _zout, = out
        if node.inputs[0].type.dtype.startswith('complex'):
            raise utils.MethodNotDefined('%s.c_code' \
                    % self.__class__.__name__)
        if len(self.c_libraries()) <= 0:
            return super(Dot22, self).c_code(node, name, (_x, _y),
                                             (_zout, ), sub)
        full_code = self.build_gemm_call() % dict(locals(), **sub)
        return full_code

    def c_code_cache_version(self):
        gv = self.build_gemm_version()
        if gv:
            return (1,) + gv
        else:
            return gv

_dot22 = Dot22()


@local_optimizer([T._dot])
def local_dot_to_dot22(node):
    # This works for tensor.outer too because basic.outer is a macro that
    # produces a dot(dimshuffle,dimshuffle) of form 4 below
    if not isinstance(node.op, T.Dot):
        return

    x, y = node.inputs
    if y.type.dtype != x.type.dtype:
        # TODO: upcast one so the types match
        _logger.info('Not optimizing dot with inputs %s %s %s %s',
                     x, y, x.type, y.type)
        return

    if y.type.dtype.startswith('float') or y.type.dtype.startswith('complex'):
        if x.ndim == 2 and y.ndim == 2:
            #print "local_dot_to_dot22: MM"
            return [_dot22(*node.inputs)]
        if x.ndim == 2 and y.ndim == 1:
            #print "local_dot_to_dot22: MV"
            return [_dot22(x, y.dimshuffle(0, 'x')).dimshuffle(0)]
        if x.ndim == 1 and y.ndim == 2:
            #print "local_dot_to_dot22: VM"
            return [_dot22(x.dimshuffle('x', 0), y).dimshuffle(1)]
        if x.ndim == 1 and y.ndim == 1:
            #print "local_dot_to_dot22: VV"
            return [_dot22(x.dimshuffle('x', 0),
                           y.dimshuffle(0, 'x')).dimshuffle()]

    _logger.info('Not optimizing dot with inputs %s %s %s %s',
                 x, y, x.type, y.type)


@local_optimizer([gemm_no_inplace])
def local_inplace_gemm(node):
    if node.op == gemm_no_inplace:
        return [gemm_inplace(*node.inputs)]


@local_optimizer([gemv_no_inplace])
def local_inplace_gemv(node):
    if node.op == gemv_no_inplace:
        return [gemv_inplace(*node.inputs)]


@local_optimizer([ger])
def local_inplace_ger(node):
    if node.op == ger:
        return [ger_destructive(*node.inputs)]


@local_optimizer([gemm_no_inplace])
def local_gemm_to_gemv(node):
    """GEMM acting on row or column matrices -> GEMV
    """
    if node.op == gemm_no_inplace:
        z, a, x, y, b = node.inputs
        if z.broadcastable == x.broadcastable == (True, False):
            r = gemv_no_inplace(z.dimshuffle(1), a, y.T, x.dimshuffle(1), b)
            return [r.dimshuffle('x', 0)]
        if z.broadcastable == y.broadcastable == (False, True):
            r = gemv_no_inplace(z.dimshuffle(0), a, x, y.dimshuffle(0), b)
            return [r.dimshuffle(0, 'x')]


@local_optimizer([gemm_no_inplace])
def local_gemm_to_ger(node):
    """GEMM computing an outer-product -> GER
    """
    if node.op == gemm_no_inplace:
        z, a, x, y, b = node.inputs
        if x.broadcastable[1] and y.broadcastable[0]:
            # x and y are both vectors so this might qualifies for a GER
            xv = x.dimshuffle(0)
            yv = y.dimshuffle(1)
            try:
                bval = T.get_scalar_constant_value(b)
            except T.NotScalarConstantError:
                # b isn't a constant, GEMM is doing useful pre-scaling
                return

            if bval == 1:   # best case a natural GER
                rval = ger(z, a, xv, yv)
                return [rval]
            elif bval == 0:   # GER on zeros_like should be faster than GEMM
                zeros = T.zeros([x.shape[0], y.shape[1]], x.dtype)
                rval = ger(zeros, a, xv, yv)
                return [rval]
            else:
                # if bval is another constant, then z is being usefully
                # pre-scaled and GER isn't really the right tool for the job.
                return


#TODO: delete this optimization when we have the proper dot->gemm->ger pipeline
#      working
@local_optimizer([_dot22])
def local_dot22_to_ger_or_gemv(node):
    """dot22 computing an outer-product -> GER
    """
    if node.op == _dot22:
        x, y = node.inputs
        xb = x.broadcastable
        yb = y.broadcastable
        one = T.as_tensor_variable(numpy.asarray(1, dtype=x.dtype))
        zero = T.as_tensor_variable(numpy.asarray(0, dtype=x.dtype))
        if xb[1] and yb[0]:
            # x and y are both vectors so this might qualifies for a GER
            xv = x.dimshuffle(0)
            yv = y.dimshuffle(1)

            zeros = T.zeros([x.shape[0], y.shape[1]], dtype=x.dtype)
            rval = ger(zeros, one, xv, yv)
            return [rval]
        if xb[0] and yb[1]:
            # x and y are both vectors so this qualifies for a sdot / ddot
            # TODO: Theano doesn't have a sdot, but gemv is better than _dot22
            xv = x.dimshuffle(1)
            zeros = T.zeros([1], x.dtype)
            rval = gemv_no_inplace(zeros, one, y.T, xv, zero)
            return [rval.dimshuffle('x', 0)]
        if xb[0] and not yb[0] and not yb[1]:
            # x is vector, y is matrix so try gemv
            xv = x.dimshuffle(1)
            zeros = T.zeros([y.shape[1]], x.dtype)
            rval = gemv_no_inplace(zeros, one, y.T, xv, zero)
            return [rval.dimshuffle('x', 0)]
        if not xb[0] and not xb[1] and yb[1]:
            # x is matrix, y is vector, try gemv
            yv = y.dimshuffle(0)
            zeros = T.zeros([x.shape[0]], dtype=x.dtype)
            rval = gemv_no_inplace(zeros, one, x, yv, zero)
            return [rval.dimshuffle(0, 'x')]


#################################
#
# Set up the BlasOpt optimizer
#
#################################

blas_optdb = SequenceDB()

# run after numerical stability optimizations (1.5)
optdb.register('BlasOpt', blas_optdb, 1.7, 'fast_run')
# run before specialize (2.0) because specialize is basically a
# free-for-all that makes the graph crazy.

blas_optdb.register('local_dot_to_dot22',
        EquilibriumOptimizer([local_dot_to_dot22], max_use_ratio=5),
        0, 'fast_run')
blas_optdb.register('gemm_optimizer',
        GemmOptimizer(),
        10, 'fast_run')
blas_optdb.register('local_gemm_to_gemv',
        EquilibriumOptimizer([
            local_gemm_to_gemv,
            local_gemm_to_ger,
            local_dot22_to_ger_or_gemv,
            local_dimshuffle_lift],
            max_use_ratio=5),
        15, 'fast_run')


# After destroyhandler is in but before we try to make elemwise things inplace
# Try to make gemm inplace
# Also, need to make the gemm optimisation(step 70) happen before the
# fusion of elemwise(step 71)
blas_opt_inplace = EquilibriumOptimizer(
            [local_inplace_gemm, local_inplace_gemv, local_inplace_ger],
            failure_callback=EquilibriumOptimizer.warn_inplace,
            max_use_ratio=5)
optdb.register('InplaceBlasOpt',
        blas_opt_inplace,
        70.0, 'fast_run', 'inplace')


class Dot22Scalar(GemmRelated):
    """Compute a matrix-matrix product.
    This is a specialization of the more general Dot()
    Used to call optimized gemm implementation.
    Also used to generate a gemm later.
    compute scalar*dot(x,y)
    """
    def make_node(self, x, y, a):
        if a.ndim != 0:
            raise TypeError(Gemm.E_scalar, a)
        if x.ndim != 2:
            raise TypeError(Gemm.E_rank, x)
        if y.ndim != 2:
            raise TypeError(Gemm.E_rank, y)

        if not (a.dtype == x.dtype == y.dtype):
            raise TypeError('Dot22Scalar requires matching dtypes',
                    (a.dtype, x.dtype, y.dtype))

        if (not a.dtype.startswith('float')
                and not a.dtype.startswith('complex')):
            raise TypeError('Dot22Scalar requires float or complex args',
                    a.dtype)

        bz = [x.type.broadcastable[0], y.type.broadcastable[1]]
        outputs = [T.tensor(x.type.dtype, bz)]
        return Apply(self, [x, y, a], outputs)

    def perform(self, node, inp, out):
        x, y, scalar = inp
        z, = out
        try:
            z[0] = numpy.asarray(scalar * numpy.dot(x, y))
        except ValueError, e:
            # The error raised by numpy has no shape information, we
            # mean to add that
            e.args = e.args + (x.shape, y.shape)
            raise

    def __str__(self):
        return "_dot22scalar"

    setup_z_Nz_Sz = Dot22.setup_z_Nz_Sz

    check_ab_double_or_float = """
        if ((PyArray_DESCR(%(_a)s)->type_num != NPY_DOUBLE)
            && (PyArray_DESCR(%(_a)s)->type_num != NPY_FLOAT))
        {PyErr_SetString(PyExc_NotImplementedError,
                         "type(a) is not double or float"); %(fail)s;}

        """
    case_float_ab_constants = """
        #define REAL float
        float a = (PyArray_DESCR(%(_a)s)->type_num == NPY_FLOAT)
        ? (REAL)(((float*)PyArray_DATA(%(_a)s))[0])
        : (REAL)(((double*)PyArray_DATA(%(_a)s))[0]);
        #undef REAL
        float b = 0.0;
        """

    case_double_ab_constants = """
        #define REAL double
        double a = (PyArray_DESCR(%(_a)s)->type_num == NPY_FLOAT)
        ? (REAL)(((float*)PyArray_DATA(%(_a)s))[0])
        : (REAL)(((double*)PyArray_DATA(%(_a)s))[0]);
        #undef REAL
        double b = 0.0;
        """

    def c_code(self, node, name, inp, out, sub):
        _x, _y, _a = inp
        _zout, = out
        if node.inputs[0].type.dtype.startswith('complex'):
            raise utils.MethodNotDefined('%s.c_code' \
                    % self.__class__.__name__)
        if len(self.c_libraries()) <= 0:
            return super(Dot22Scalar, self).c_code(node, name, (_x, _y),
                                                   (_zout, ), sub)
        full_code = self.build_gemm_call() % dict(locals(), **sub)
        return full_code

    def c_code_cache_version(self):
        gv = self.build_gemm_version()
        if gv:
            return (2,) + gv
        else:
            return gv

_dot22scalar = Dot22Scalar()


@local_optimizer([T.mul])
def local_dot22_to_dot22scalar(node):
    """
    :note: we upcast the scalar if after the multiplication with the
        dot this give the same type.

    .. note: We execute this optimizer after the gemm optimizer. This
        allow to give more priority to gemm that give more speed up
        then this optimizer, but allow the gemm optimizer to ignore
        this op.


    TODO: support when we can reorder the mul to generate a
    dot22scalar or fix the canonizer to merge them(1 mul with multiple
    inputs)
    """
    if node.op != T.mul:
        return False
    i_dot22 = [x.owner and x.owner.op == _dot22 for x in node.inputs]
    if not any(i_dot22):
        return False  # no dot22
    if i_dot22.count(True) > 1:
        #TODO: try each of them.
        pass
        #return False #TODO fix
    dot22_idx = i_dot22.index(True)
    d = node.inputs[dot22_idx]
    i_scalar = [_as_scalar(x, dtype=d.dtype) for x in node.inputs]
    if not any(i_scalar):
        i_mul = [x.owner and x.owner.op == T.mul for x in node.inputs]
        if not any(i_mul):
            #no scalar in input and no multiplication
            #if their was a multiplication we couls reorder the graph
            #by the associativity of the graph.
            return False

        #maybe we can reorder the graph as this mul have a mul in input.
        #The canonizer should have merged those mul together.
        #We support only 1 additional level of mul.
        mul_idx = i_mul.index(True)  # we take the first mul!
        m = node.inputs[mul_idx]

        if len(m.owner.inputs) == 2 and any([_as_scalar(x, dtype=d.dtype)
                                             for x in m.owner.inputs]):
            scalar_idx = -1
            for i, x in enumerate(m.owner.inputs):
                if _as_scalar(x, dtype=d.dtype) and (theano.scalar.upcast(
                        x.type.dtype, d.type.dtype)
                                      == d.type.dtype):
                    scalar_idx = i
                    break

            if scalar_idx < 0:
                _logger.info('Not optimizing dot22 with inputs %s %s, as the'
                             ' type of the scalar cannot be upcasted to the'
                             ' matrix type',
                             node.inputs, [x.type for x in node.inputs])
                return False
            a = T.cast(_as_scalar(m.owner.inputs[scalar_idx],
                                  dtype=d.dtype), d.type.dtype)
            assert not a.type.ndim
            dot = _dot22scalar(d.owner.inputs[0], d.owner.inputs[1], a)

            # What about the other inputs to the original node that were
            # neither part of the dot22 or this mul?
            # I'm asserting there are no such inputs here:
            assert dot22_idx != mul_idx
            assert all((i in (dot22_idx, mul_idx))
                    for i in xrange(len(node.inputs)))

            return [T.mul(m.owner.inputs[1 - i], dot)]
        elif m.owner and m.owner.op == T.mul:
            _logger.info('Not optimizing dot22 with inputs %s %s %s %s. '
                    'we need to check in a recursive way in the mul if we can '
                    'reorder the graph. The canonizer should have done this.',
                    d, m, d.type, m.type)
        else:
            return False

    scalar_idx = -1
    for i, x in enumerate(node.inputs):
        if (i_scalar[i] is not None
                and (theano.scalar.upcast(x.type.dtype, d.type.dtype)
                    == d.type.dtype)):
            scalar_idx = i
            break
    if scalar_idx < 0:
        _logger.info('Not optimizing dot22 with inputs %s %s, as the type '
                'of the scalar cannot be upcasted to the matrix type',
                node.inputs, [x.type for x in node.inputs])
        return False
    assert scalar_idx < len(node.inputs)
    s = node.inputs[scalar_idx]
    o = copy.copy(node.inputs)
    o.remove(d)
    o.remove(s)

    a = T.cast(i_scalar[scalar_idx], d.type.dtype)
    assert not a.type.ndim
    if len(o) == 0:
        return [_dot22scalar(d.owner.inputs[0], d.owner.inputs[1], a)]
    else:
        return [T.mul(_dot22scalar(d.owner.inputs[0],
                                   d.owner.inputs[1], a), *o)]

#must happen after gemm as the gemm optimizer don't understant
#dot22scalar and gemm give more speed up then dot22scalar
blas_optdb.register('local_dot22_to_dot22scalar',
        EquilibriumOptimizer([local_dot22_to_dot22scalar], max_use_ratio=5),
        11, 'fast_run')


#from opt import register_specialize, register_canonicalize
#@register_specialize
@local_optimizer([])
def local_print_as_we_go_along(node):
    if node.op in (T.sub, T.add):
        debugprint(node)
