At this moment relu_layer op doesn't allow threshold configuration, and legacy RELU op allows that.
We should add configuration option to relu_layer.

Add quickselect algorithm. Quickselect is a selection algorithm to find the kth smallest element in an unordered list.

Forgive me if this already exists, because I couldn't find it in the docs, but is there a way to construct a matrix row-by-row using an iterator? (for cases when source data structure already represents them in row-by-row form)

Currently the only way I found is creating matrix NxM using from_iterator, and then invoking transpose to get MxN, but this is rather inefficient - first, it nee