torch.max(r,1./r).max(2)[0]

This expression uses PyTorch functions to compute the maximum values of a tensor `r` along two dimensions.

Here's a breakdown of what's happening:

1. `torch.max(r, 1./r)` computes the element-wise maximum between `r` and `1./r`. This essentially creates a new tensor where each element is the maximum of the corresponding elements in `r` and `1./r`.

2. `max(2)` applies the `max` function along the second dimension of the tensor, returning a tuple of two tensors: the maximum values along that dimension, and their corresponding indices.

3. `[0]` selects the first tensor in the tuple, which contains the maximum values along the second dimension.

So, the overall expression computes the maximum values of `r` along the second dimension, but also takes into account the reciprocal values of `r` by computing the maximum with `1./r`.