#!/usr/bin/python3

import torch


def fun(x):
    return 2*x**4 - x**3 + 3.5*x + 10


x = torch.tensor(5., requires_grad=True)

learning_rate = torch.tensor(0.01)

for _ in range(100):
    y = fun(x)
    print(x, " => ", y)
    y.backward()

    with torch.no_grad():
        x = x - learning_rate * x.grad

    x.requires_grad_(True)