bisect, newton,...

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Tue Oct 22 11:17:19 2019

@author: student
"""

import numpy as np
import matplotlib.pyplot as plt
import scipy.optimize as opt

def f1(t):
    return t**3 - 6*t**2 + 11*t +np.cos(t/10) - 50

def f2(t, a, b):
    return t**3 - 6*t**2 + 11*t +np.cos(t/a) - b

def der_f1(t):
    return 3*t**2 - 12*t + 11 - 0.1*np.sin(t/10)

x1 =  np.linspace(-5,8,200)
y1 = f1(x1)

#xl = float(input('odaberi xlijevo: '))
#print(xl, type(xl))


def bisekcija():
    xl =-4
    xd = 7
    if f1(xl)*f1(xd)>0:
        print(' nije dobro!')

    sol = 1

    yl =f1(xl)
    yd = f1(xd)

    brojac = 0
    while sol > 1.e-04:

    #plt.plot(xl, yl, 'o')
    #plt.plot(xd, yd, 'o')

        xs = (xl+xd)/2
        ys = f1(xs)
    #plt.plot(xs, ys, 'D')

        sol = np.abs(ys)


        if yl *ys <0:
            xd = xs
        else:
            xl = xs
        if brojac > 3:
            break

        brojac  += 1


    print('xs :', xs)
    xb = opt.bisect(f1, -5, 8)
    print("xb: ", xb)

    plt.plot(x1, y1)

#plt.plot([xl,xd], [yl,yd], #linewidth = 4,
#         linestyle ='--',
#         color = 'salmon',
#         marker = 'D',
#         markersize = 10)
    plt.axhline(0, color='r')     #traženje nultoče
    plt.show()


def newton():
    x = np.linspace(-5, 8, 200)
    y = f1(x)

    x0 = 8
    y0 = f1(x0)
    sol = np.abs(y0)
    brojac = 0
    while sol  > 1.e-04:

        x1 = x0 - f1(x0)/ der_f1(x0)
        y1 = f1(x1)
        plt.plot([x0, x1, x1], [y0, 0, y1], "-D")
        x0 = x1
        y0 = f1(x0)
        sol = np.abs(y0)
        brojac += 1
        if brojac > 100:
            break
    print("x1: ", x1)
    nx = opt.newton(f1, 8)
    print("nx: ", nx)
    fx = opt.fsolve(f1, 8)
    print("fx: ", fx, type(fx))
    plt.plot(x, y)
    plt.axhline(0, c = "r")
    plt.show()

#newton()


def nova():
    x = np.linspace(-5, 8, 200)
    y = f2(x, a = 10, b = 50)
    fx = opt.fsolve(f1, 8)
    print("fx: ", fx, type(fx))
    fx = opt.fsolve(f2, 8, args = (10, 50))     # args = argumenti
    print("fx: ", fx, type(fx))
    plt.plot(x, y)
    plt.axhline(0, c = "r")
    plt.plot(plt.xlim(), [100, 100], "g")
    plt.show()


if __name__ == "__main__":
    nova()