2

# -*- coding: utf-8 -*-

import matplotlib
import matplotlib.pyplot as plt
import math

n = 20000
h = 0.000051
y = [1]
z = [5]
t = [6]
x = []
for i in range (0, n):
    x.append(i*h)

for _ in range (1, n):
    tmp_y = y[-1] + h*(z[-1])
    tmp_z = z[-1] + h*(t[-1])
    tmp_t = t[-1] + h*(-12*t[-1] - 48*z[-1] - 64*y[-1])
    y.append(tmp_y)
    z.append(tmp_z)
    t.append(tmp_t)
x1 = [0]
y1 = [1]
for i in range (1, n):
    x1.append(i*h)
    y1.append(math.exp((-4)*x1[-1]) + 9*x1[-1]*math.exp((-4)*x1[-1]) + 31*math.exp((-4)*x1[-1])*x1[-1]**2)
plt.plot(x,y)
plt.plot(x1,y1)
plt.show()

d = []
for i in range(1, n):
   d.append(abs(y[i]-y1[i])/y[i])

print(max(d)*100, '%')