import numpy as np
import matplotlib.pyplot as plt

def f(x1, x2):
    return x1**2+2*x1+x2**2+x2

def gradf(x1, x2):
    gradx1 = 2*x1+2
    gradx2 = 2*x2+1
    return gradx1,gradx2

x1, x2 = 1, 1
y = f(x1, x2)

eta = 0.2

for step in range(1000):
    gradf1, gradf2 = gradf(x1, x2)
    x1t = x1 - eta*gradf1
    x2t = x2 - eta*gradf2
    yt = f(x1t, x2t)
    if (yt < y):
        x1 = x1t
        x2 = x2t
        y = yt
    else:
        continue
    print(step, x1, x2, y)