import numpy as np
import matplotlib.pyplot as plt

def f(x):
    return (0.25*x - 2)*np.sin(3*x)


n = 10000  # number of x-values
x = np.linspace(-5, 5, n)
x_sol_array = np.array([]) 

for i in range(0, n-1):    
    if f(x[i])*f(x[i+1]) <= 0:
        x_sol = (x[i] + x[i+1])/2
        print(f'Losning: {x_sol:.2f}') 
        x_sol_array = np.append(x_sol_array, x_sol) 
        

filename = 'bf_losning.csv'

np.savetxt(filename, x_sol_array.T, fmt='%.2e')   

plt.close('all')
plt.plot(x, f(x))
plt.grid()
plt.plot(x_sol_array, f(x_sol_array), 'r*')
plt.xlabel('x')
plt.ylabel('f(x)')

# plt.savefig('losn_likn_bf.pdf')
plt.show()