3

# -*- coding: utf-8 -*-
import matplotlib
import matplotlib.pyplot as plt
import math

n = 20000
h = 0.0001
e = math.exp(1)
y = [0]
z = [0]
t = [0]
x = []
for i in range (0, n):
    x.append(i*h)

for i in range (1, n):
    tmp_y = y[-1] + h*(z[-1])
    tmp_z = z[-1] + h*(t[-1])
    tmp_t = t[-1] + h*(12 - 12*t[-1] - 48*z[-1] - 64*y[-1])
    y.append(tmp_y)
    z.append(tmp_z)
    t.append(tmp_t)
x1 = [0]
y1 = [0]
for i in range (1, n):
    x1.append(i*h)
    y1.append((3/16) - (3/16)*e**((-4)*x1[-1]) - (3/4)*x1[-1]*e**((-4)*x1[-1]) - (3/2) * x1[-1]**2 * e**((-4) * x1[-1]))
plt.plot(x,y)
plt.plot(x1,y1)
plt.show()

d = []
for i in range(1, n):
    if i > 10000:
        d.append(abs(y[i]-y1[i])/y[i])
print(max(d)*100, '%')