Add Inverse to autograd (pytorch#1670)

* Add Inverse to autograd * Add SkipTest to autograd tests

Author: fmassa

test/test_autograd.py

@@ -10,7 +10,7 @@
 from torch.autograd import gradcheck
 from torch.autograd.function import once_differentiable
 
-from common import TestCase, run_tests
+from common import TestCase, run_tests, skipIfNoLapack
 from torch.autograd._functions import *
 from torch.autograd import Variable, Function
 
@@ -1415,6 +1415,7 @@ class dont_convert(tuple):
  (Trace, (), ((S, S),)),
  (Cross, (), ((S, 3), (S, 3))),
  (Cross, (1,), ((S, 3, S), (S, 3, S)), 'dim'),
+ (Inverse, (), ((S, S),), '', (), [skipIfNoLapack]),
  (Clone, (), ((S, M, S),)),
  (Squeeze, (), ((S, 1, M, 1),)),
  # TODO: enable neg dim checks
@@ -1542,6 +1543,7 @@ class dont_convert(tuple):
  ('trace', (M, M), ()),
  ('cross', (S, 3), ((S, 3),)),
  ('cross', (S, 3, S), ((S, 3, S), 1), 'dim'),
+ ('inverse', (S, S), (), '', (), [skipIfNoLapack]),
  ('clone', (S, M, S), ()),
  ('eq', (S, S, S), ((S, S, S),)),
  ('ne', (S, S, S), ((S, S, S),)),
@@ -1617,6 +1619,8 @@ def unpack_variables(args):
 
  dim_args_idx = test[4] if len(test) == 5 else []
 
+ skipTestIf = test[5] if len(test) == 6 else []
+
  for dim_perm in product([-1, 1], repeat=len(dim_args_idx)):
  test_name = basic_test_name
  new_constructor_args = [arg * dim_perm[dim_args_idx.index(i)] if i in dim_args_idx else arg
@@ -1671,6 +1675,10 @@ def apply_inplace_fn(*input):
  self.assertEqual(inp_i.grad, i.grad)
 
  assert not hasattr(TestAutograd, test_name), 'Two tests have the same name: ' + test_name
+
+ for skip in skipTestIf:
+ do_test = skip(do_test)
+
  setattr(TestAutograd, test_name, do_test)
 
 
@@ -1687,6 +1695,8 @@ def apply_inplace_fn(*input):
 
  dim_args_idx = test[4] if len(test) == 5 else []
 
+ skipTestIf = test[5] if len(test) == 6 else []
+
  for dim_perm in product([-1, 1], repeat=len(dim_args_idx)):
  test_name = basic_test_name
  new_args = [arg * dim_perm[dim_args_idx.index(i)] if i in dim_args_idx else arg for i, arg in enumerate(args)]
@@ -1726,6 +1736,10 @@ def check(name):
  raise
 
  assert not hasattr(TestAutograd, test_name), 'Two tests have the same name: ' + test_name
+
+ for skip in skipTestIf:
+ do_test = skip(do_test)
+
  setattr(TestAutograd, test_name, do_test)
 
 

torch/autograd/_functions/linalg.py

@@ -69,3 +69,17 @@ def backward(self, grad_output):
  grad_input = torch.cross(other, grad_output, self.dim)
  grad_other = torch.cross(grad_output, input, self.dim)
  return grad_input, grad_other
+
+
+class Inverse(Function):
+
+ @staticmethod
+ def forward(ctx, input):
+ inverse = torch.inverse(input)
+ ctx.save_for_backward(inverse)
+ return inverse
+
+ @staticmethod
+ def backward(ctx, grad_output):
+ inverse, = ctx.saved_variables
+ return -torch.mm(inverse.t(), torch.mm(grad_output, inverse.t()))

torch/autograd/variable.py

@@ -716,6 +716,9 @@ def trace(self):
  def cross(self, other, dim=-1):
  return Cross(dim)(self, other)
 
+ def inverse(self):
+ return Inverse.apply(self)
+
  def multinomial(self, num_samples=1, with_replacement=False):
  return Multinomial(num_samples, with_replacement)(self)