采用全选主元高斯消去法，求解复系数线性方程组。其中ar存方程组复系数矩阵实部，ai存虚部。br存右端向量实部，返回解向量实部；bi存右端向量虚部，返回解向量虚部。-With full pivoting Gaussian elimination, solving linear equations. Ar equations which keep the real part of complex coefficient matrix, ai keep the imaginary part. br keep the real part of the right end of vector, returns solution vectors of the real part　bi deposit right end of the vector imaginary part, imaginary part to return solution vector.