matlab编程的三个线性方程组求解子程序：cggm.m,fdm.m,febs.m.其中cggm.m为共轭梯度法求解子程序,fdm.m为最速下降法求解自程序,febs.m为三对角追赶法求解子程序.-Matlab programming three linear equations subroutine : cggm.m, fdm.m. febs.m. which cggm.m to conjugate gradient method subroutine, fdm.m for the steep