Write value_of and value_of_rec in a more efficient way

[randommm]

Summary:

Write value_of and value_of_rec for matrix in a more efficient way.

Description:

value_of and value_of_rec for matrix are written in a inefficient way that calls mat(i, j), mat.rows() and mat.cols() on each iteration of the loop.

Sizes should be stored in a temporary int and the matrix data pointer in a temporary T*.

Current Version:

v2.9.0