Make some expm grad test always be in float64 for numerical stability of the test.

theano/tensor/tests/test_slinalg.py

@@ -251,10 +251,11 @@ def test_expm_grad_1():
     if not imported_scipy:
         raise SkipTest("Scipy needed for the expm op.")
     rng = numpy.random.RandomState(utt.fetch_seed())
-    A = rng.randn(5, 5).astype(config.floatX)
+    # Always test in float64 for better numerical stability.
+    A = rng.randn(5, 5)
     A = A + A.T
 
-    tensor.verify_grad(expm, [A,], rng=rng)
+    tensor.verify_grad(expm, [A], rng=rng)
 
 
 def test_expm_grad_2():
@@ -262,12 +263,13 @@ def test_expm_grad_2():
     if not imported_scipy:
         raise SkipTest("Scipy needed for the expm op.")
     rng = numpy.random.RandomState(utt.fetch_seed())
-    A = rng.randn(5, 5).astype(config.floatX)
-    w = (rng.randn(5).astype(config.floatX))**2
+    # Always test in float64 for better numerical stability.
+    A = rng.randn(5, 5)
+    w = rng.randn(5)**2
     A = (numpy.diag(w**0.5)).dot(A + A.T).dot(numpy.diag(w**(-0.5)))
     assert not numpy.allclose(A, A.T)
 
-    tensor.verify_grad(expm, [A,], rng=rng)
+    tensor.verify_grad(expm, [A], rng=rng)
 
 
 def test_expm_grad_3():
@@ -275,6 +277,7 @@ def test_expm_grad_3():
     if not imported_scipy:
         raise SkipTest("Scipy needed for the expm op.")
     rng = numpy.random.RandomState(utt.fetch_seed())
-    A = rng.randn(5, 5).astype(config.floatX)
+    # Always test in float64 for better numerical stability.
+    A = rng.randn(5, 5)
 
-    tensor.verify_grad(expm, [A,], rng=rng)
+    tensor.verify_grad(expm, [A], rng=rng)