求共轭梯度法解任意线性方程组的c++代码

老师布置的期末作业，要用c++做
网上搜的matlab程序附上，作为参考
function x = cg(A,b)
tol=1e-10;
r = b + A*b;w = -r;
z = A*w;
s = w'*z;
t = (r'*w)/s;
x = -b + t*w;
for k = 1:numel(b);
r = r - t*z;
if( norm(r) < tol )
return;
end B = (r'*z)/s;
w = -r + B*w;
z = A*w;
s = w'*z;
t = (r'*w)/s;
x = x + t*w;
end
求助各位大神了，另附百度知道问题地址
http://zhidao.baidu.com/question/506931593.html?quesup2