U method
Return upper triangular factor return U
Implementation
Array2d U() {
var U = Array2d.fixed(_n, _n);
for (var i = 0; i < _n; i++) {
for (var j = 0; j < _n; j++) {
if (i <= j) {
U[i][j] = _LUMatrix[i][j];
} else {
U[i][j] = 0.0;
}
}
}
return U;
}