modified elemwise to reuse output storage when possible. this sped it up

elemwise.py

@@ -202,8 +202,8 @@ class RecAlgo(object):
 
 class NaiveAlgo(object):
     verbose = False
-    #cache_version = ()
-    cache_version = ('debug', 2)
+    cache_version = ()
+    cache_version = ('debug', 3)
 
     def __init__(self, scalar_op):
         self.scalar_op = scalar_op
@@ -893,11 +893,13 @@ class NaiveAlgo(object):
 
         for oname in outputs:
             print >> sio, """
-        if (cnda_%(oname)s) {
-            //TODO: check if we can maybe use existing storage
+        for (int i = 0; (i< %(nd)s) && (cnda_%(oname)s); ++i) {
+            if (dims[i] != CudaNdarray_HOST_DIMS(cnda_%(oname)s)[i])
+            {
                 Py_DECREF(cnda_%(oname)s);
                 cnda_%(oname)s = NULL;
             }
+        }
         if (NULL == cnda_%(oname)s)
         {
             cnda_%(oname)s = (CudaNdarray*)CudaNdarray_new_null();