2-01.py

import numpy as np
import matplotlib.pyplot as plt
import scipy.integrate as integ
from scipy.integrate import quad
import scipy.interpolate as intrp

def func(y, x):
    return -y+np.sin(100/(x**2+1))

x = np.linspace(0, 20, 1000)
a0 = 5
b0 = -2

#nacrtaj
y_a = integ.odeint(func, a0, x)
plt.plot(x, y_a, 'b--', label='y_a')

y_b = integ.odeint(func, b0, x)
plt.plot(x, y_b, 'g--', label='y_b')

#integriraj
f1 = intrp.interp1d(x, y_a.squeeze(), kind='quadratic')
f2 = intrp.interp1d(x, y_b.squeeze(), kind='quadratic')

p1, _ = quad(f1, 0, 20)
p2, _ = quad(f2, 0, 20)
print(np.abs(p2-p1))

#oboji
plt.fill_between(x, y_a.squeeze(), y_b.squeeze(), color='lightgreen')

x, y = np.loadtxt('rm-python_2.001.dat', unpack=True)
plt.plot(x, y, 'r+')

#regresija
X = np.linspace(0, 20, 1000)
#za crtanje grafova, mali x ima premalo tocaka a i nije sortiran

coeff = np.polyfit(x, y, 2)
f3 = np.poly1d(coeff)
plt.plot(X, f3(X), '--', color='black')

coeff = np.polyfit(x, y, 3)
f4 = np.poly1d(coeff)
plt.plot(X, f4(X), '--', color='grey')

plt.legend()
plt.show()