public static Matrix <Td, Tv> SetByCoordParallelY <Td, Tv>(
this Matrix <Td, Tv> mat, Func <long, long, Tv> x_y_valueFun)
{
Parallel.For(mat.FY, mat.EY, y => mat.SubXVectorWindow(y).SetByCoord(x => x_y_valueFun(x, y)));
return(mat);
}