static ref BlockMatrix <M, N, double> Mul <M, K, N>(BlockMatrix <M, K, double> A, BlockMatrix <K, N, double> B, ref BlockMatrix <M, N, double> X)
where M : ITypeNat, new()
where K : ITypeNat, new()
where N : ITypeNat, new()
{
var m = nati <M>();
var n = nati <N>();
for (var i = 0; i < m; i++)
{
var row = A.GetRow(i);
for (var j = 0; j < n; j++)
{
var col = B.GetCol(j);
X[i, j] = Dot(row, col);
}
}
return(ref X);
}