共轭梯度法python实现FR

# FR格式共轭梯度法的Python实现示例
import numpy as np

def FR_CG(x0, A, b, max_iter=100, tol=1e-5):
    x = x0
    r = b - np.dot(A, x)
    p = r
    rsold = np.dot(r, r)
    for i in range(max_iter):
        Ap = np.dot(A, p)
        alpha = rsold / np.dot(p, Ap)
        x = x + alpha * p
        r = r - alpha * Ap
        rsnew = np.dot(r, r)
        if np.sqrt(rsnew) < tol:
            break
        p = r + (rsnew / rsold) * p
        rsold = rsnew
    return x