Hi,

i have input image with size(1,1,28,28) and output image y with the same size. y= cnn(x)

and i want to calculate the gradient between every output pixel image with respect to every pixel from input image but i have : RuntimeError: Mismatch in shape: grad_output[0] has a shape of torch.Size([784]) and output[0] has a shape of torch.Size([]).

my cod is :

def jacobian(y, x, create_graph=False):

```
jac = []
y = cnn(x)
x.requires_grad_(True)
flat_y = y.reshape(-1)
flat_x = x.reshape(-1)
#y= cnn(flat_x)
grad_y = torch.zeros_like(flat_y)
for i in range(len(flat_y)):
for j in range(len(flat_x)):
grad_y[i] = 1.
grad_x,= torch.autograd.grad(flat_y[i] ,flat_x[j],grad_y,retain_graph=True,create_graph= create_graph,allow_unused=True)
jac.append(grad_x.reshape(x.shape))
grad_y[i] = 0.
return torch.stack(jac).reshape(y.shape + x.shape)
```

print( jacobian (y,x,create_graph = True) )

could someone help me why i have this error?