FromVec broadcasting, increase torch version

Author: zachteed

Diff for: README.md

@@ -25,7 +25,7 @@ Zachary Teed and Jia Deng, CVPR 2021
 
 ### Requirements: 
  * Cuda >= 10.1 (with nvcc compiler)
- * PyTorch >= 1.7
+ * PyTorch >= 1.8
 
 We recommend installing within a virtual enviornment. Make sure you clone using the `--recursive` flag. If you are using Anaconda, the following command can be used to install all dependencies
 ```

Diff for: lietorch/group_ops.py

@@ -83,7 +83,7 @@ def forward(cls, ctx, group_id, *inputs):
     def backward(cls, ctx, grad):
         inputs = ctx.saved_tensors
         J = lietorch_backends.projector(ctx.group_id, *inputs)
-        return None, torch.matmul(grad.unsqueeze(-2), torch.linalg.pinv(J))
+        return None, torch.matmul(grad.unsqueeze(-2), torch.linalg.pinv(J)).squeeze(-2)
 
 class ToVec(torch.autograd.Function):
     """ convert group object to vector """
@@ -98,5 +98,5 @@ def forward(cls, ctx, group_id, *inputs):
     def backward(cls, ctx, grad):
         inputs = ctx.saved_tensors
         J = lietorch_backends.projector(ctx.group_id, *inputs)
-        return None, torch.matmul(grad.unsqueeze(-2), J)
+        return None, torch.matmul(grad.unsqueeze(-2), J).squeeze(-2)
 

Diff for: lietorch/run_tests.py

@@ -218,7 +218,7 @@ def fn(a):
         return Group.InitFromVec(a).vec()
 
     D = Group.embedded_dim
-    a = torch.randn(1, D, requires_grad=True, device=device).double()
+    a = torch.randn(1, 2, D, requires_grad=True, device=device).double()
 
     analytical, numerical = gradcheck(fn, [a], eps=1e-4)