torch.stft returns real and imaginary components as the last dimension. Two very frequent functions to consume it are: abs and angle (in NumPy). Abs is similar to regular np.hypot, so meanwhile complex tensor support is not developed, hypot could do abs's job.

NumPy also has a hypot, although it accepts two arrays. We may have two versions: one accepting two arrays, another accepting only one array and a dim. Essentially, hypot is a version of norm, specialized for two element vectors only.