code: function embed(mat, rows, cols) {
                              var r = mat.rows;
                              var c = mat.columns;
                              if ((r === rows) && (c === cols)) {
                                  return mat;
                              } else {
                                  var resultat = Matrix.zeros(rows, cols);
                                  resultat = resultat.setSubMatrix(mat, 0, 0);
                                  return resultat;
                              }
                          }
docs: Put a matrix into the top left of a matrix of zeros. `rows` and `cols` are the dimensions of the output matrix.