lab3.py

import math

from labs.lab2 import runge


def f(x, y):
    # return y * math.log(y) / x
    return (y * y + x * y) / (x * x)


def adams(h):
    start = 1
    end = 2
    length = int(math.fabs(end - start) / h + 1)
    x = [0] * length
    y = [0] * length
    x[0] = start
    y[0] = 1

    trash, y2 = runge(h)
    for i in range(0, 4):
        x[i + 1] = x[i] + h
        y[i] = y2[i]

    for i in range(4, length):
        x[i] = x[i - 1] + h
        y[i] = y[i - 1] + h / 24 * (
            55 * f(x[i - 1], y[i - 1])
            - 59 * f(x[i - 2], y[i - 2])
            + 37 * f(x[i - 3], y[i - 3])
            - 9 * f(x[i - 4], y[i - 4])
        )
    # print(y)
    return x, y