解Ax = b, A =下三角矩阵c++。

I`m trying to do this function that solves linear systems, A*x = b, where A = lower triangular matrix, linear independent matrix and with only one solution. But the results always show 0 0 0 0 ... I have printed the sum, s, and it always shows 0 as well...I`m trying to do this function that solves line