0.618法（近似黄金分割法）实验

def face(x):
    return x**3-2*x+1  #目标函数

def mark(a,b):
    if a>=b:
        return ">="
    else:
        return "<"

def HJFG(a,b,eps):
    lamb=0.618
    t1=a+(1-lamb)*(b-a)
    t2=a+lamb*(b-a)
    f1=face(t1)
    f2=face(t2)
    i=0
    print("第",i,"次迭代")
    print("a      b     t1     t2     f1      f2")
    print(‘%.3f‘ %a, ‘%.3f‘ %b, ‘%.3f‘ %t1, ‘%.3f‘ %t2, ‘%.3f‘ %f1,mark(f1,f2), ‘%.3f‘ %f2)
    while(b-a>eps):
        i=i+1
        print("第", i, "次迭代")
        print("a      b     t1     t2     f1      f2")
        if f1<=f2:   #第三步
            if t2-a<=eps:  #第四步
                print("近似最优解为", ‘%.3f‘ % t1)
                break
            else:
                b=t2
                t2=t1
                t1=b-lamb*(b-a)
                f2=f1
                f1=face(t1)
                print(‘%.3f‘ % a, ‘%.3f‘ % b, ‘%.3f‘ % t1, ‘%.3f‘ % t2, ‘%.3f‘ % f1, mark(f1, f2), ‘%.3f‘ % f2)
        else:
            if b-t1<=eps:
                print("近似最优解为",‘%.3f‘ % t2)
                break
            else:
                a=t1
                t1=t2
                t2=a+lamb*(b-a)
                f1=f2
                f2=face(t2)
                print(‘%.3f‘ % a, ‘%.3f‘ % b, ‘%.3f‘ % t1, ‘%.3f‘ % t2, ‘%.3f‘ % f1, mark(f1, f2), ‘%.3f‘ % f2)


HJFG(0,3,0.5)