pythonnumerical-analysisbisection

Solving equation using bisection method

Is there a bisection method I can find online, specifically for python?

For example, given these equations how can I solve them using the bisection method?

x^3 = 9  
3 * x^3 + x^2 = x + 5  
cos^2x + 6 = x
Solution

  • Using scipy.optimize.bisect:

    import scipy.optimize as optimize
import numpy as np

def func(x):
    return np.cos(x)**2 + 6 - x

# 0<=cos(x)**2<=1, so the root has to be between x=6 and x=7
print(optimize.bisect(func, 6, 7))
# 6.77609231632

    optimize.bisect calls _zeros._bisect, which is implemented in C.