added arccos

theano/scalar/basic.py

@@ -1716,6 +1716,22 @@ class Cos(UnaryScalarOp):
         return "%(z)s = cos(%(x)s);" % locals()
 cos = Cos(upgrade_to_float, name = 'cos')
 
+class Arccos(UnaryScalarOp):
+    def impl(self, x):
+        return numpy.arccos(x)
+    def grad(self, (x, ), (gz, )):
+        if gz.type in complex_types:
+            raise NotImplementedError()
+        if x.type in float_types:
+            return - gz / sqrt(numpy.cast[x.type](1) - sqr(x)),
+        else:
+            return None,
+    def c_code(self, node, name, (x, ), (z, ), sub):
+        if node.inputs[0].type in complex_types:
+            raise NotImplementedError('type not supported', type)
+        return "%(z)s = acos(%(x)s);" % locals()
+arccos = Arccos(upgrade_to_float, name = 'cos')
+
 class Sin(UnaryScalarOp):
     def impl(self, x):
         return numpy.sin(x)

theano/tensor/basic.py

@@ -2284,6 +2284,10 @@ def sqrt(a):
 def cos(a):
     """cosine of a"""
 
+@_scal_elemwise_with_nfunc('arccos',1,1)
+def arccos(a):
+    """arccosine of a"""
+
 @_scal_elemwise_with_nfunc('sin', 1, 1)
 def sin(a):
     """sine of a"""

theano/tensor/inplace.py

@@ -144,6 +144,10 @@ def sqrt_inplace(a):
 def cos_inplace(a):
     """cosine of `a` (inplace on `a`)"""
 
+@_scal_inplace
+def arccos_inplace(a):
+    """arccosine of `a` (inplace on `a`)"""
+
 @_scal_inplace
 def sin_inplace(a):
     """sine of `a` (inplace on `a`)"""

theano/tensor/tests/test_basic.py

@@ -791,6 +791,16 @@ _grad_broadcast_unary_wide = dict(normal = (rand_ranged(-1000, 1000, (2, 3)),),
                                   #empty = (numpy.asarray([]),),
                                   )
 
+_good_broadcast_unary_arccos = dict(normal = (rand_ranged(-1.+1e-7, 1.-1e-7, (2, 3)),),
+                                  integers = (randint_ranged(-1.+1e-7, 1-1e-7, (2, 3)),),
+                                  complex = (randc128_ranged(-1.+1e-7, 1-1e-7, (2, 3)),),
+                                  empty = (numpy.asarray([]),),)
+
+_grad_broadcast_unary_arccos = dict(normal = (rand_ranged(-1.+1e-7, 1-1e-7, (2, 3)),),
+                                  #complex = (randc128_ranged(-1000, 1000, (2, 3)),),
+                                  #empty = (numpy.asarray([]),),
+                                  )
+
 
 SinTester = makeBroadcastTester(op = sin,
                                   expected = numpy.sin,
@@ -811,6 +821,15 @@ CosInplaceTester = makeBroadcastTester(op = inplace.cos_inplace,
                                          good = _good_broadcast_unary_wide,
                                          grad = _grad_broadcast_unary_wide,
                                          inplace = True)
+ArccosTester = makeBroadcastTester(op = arccos,
+                                  expected = numpy.arccos,
+                                  good = _good_broadcast_unary_arccos,
+                                  grad = _grad_broadcast_unary_arccos)
+ArccosInplaceTester = makeBroadcastTester(op = inplace.arccos_inplace,
+                                         expected = numpy.arccos,
+                                         good = _good_broadcast_unary_arccos,
+                                         grad = _grad_broadcast_unary_arccos,
+                                         inplace = True)
 
 tan_grad_rtol = None
 if config.floatX=='float32':