When as_tuple is FALSE (default):
Returns a tensor containing the indices of all non-zero elements of
input. Each row in the result contains the indices of a non-zero
element in input. The result is sorted lexicographically, with
the last index changing the fastest (C-style).
If input has \(n\) dimensions, then the resulting indices tensor
out is of size \((z \times n)\), where \(z\) is the total number of
non-zero elements in the input tensor.
When as_tuple is TRUE:
Returns a tuple of 1-D tensors, one for each dimension in input,
each containing the indices (in that dimension) of all non-zero elements of
input .
If input has \(n\) dimensions, then the resulting tuple contains \(n\)
tensors of size \(z\), where \(z\) is the total number of
non-zero elements in the input tensor.
As a special case, when input has zero dimensions and a nonzero scalar
value, it is treated as a one-dimensional tensor with one element.