torch:var

(torch:var a &key axis keepdims ddof)

Differentiable variance with the (n - ddof) divisor (linalg:var's rules: the default :ddof 0 is torch's unbiased=False, :ddof 1 the sample variance). It is composed from torch:mean, torch:sub, torch:mul and torch:sum, so its backward pass comes from the tape.