求矩阵行列式

double det() {for (int i = 1; i < n; i++) {for (int j = 0; j < i; j++)if (A[i][j] != 0) {for (int k = j + 1; k < n; k++)A[i][k] -= (A[j][k] * A[i][j] / A[j][j]);A[i][j] = 0;}}double ans = 1;for (int i = 0; i < m * m - 1; i++)ans *= A[i][i];return ans;}