Bisection Step

Problem

Perform one step of the bisection method on the continuous function f(x) = sum(coeffs[i] * x^i) with bracket [a, b].

Return the new bracket [lo, hi] as a two-element list. If f at the midpoint is exactly 0.0, return [midpoint, midpoint].

Hint

Keep the half where f changes sign by comparing f(a) * f(mid) with 0.

case 1

in: [[-2,0,1],1,2]

expected: [1,1.5]

case 2

in: [[-2,-1,0,1],1,2]

expected: [1.5,2]

case 3

in: [[0,1],-1,1]

expected: [0,0]

case 4

in: [[-4,0,1],0,3]

expected: [1.5,3]

Starter codePython

def bisection_step(coeffs, a, b):
    # Return the new bracket [lo, hi]
    # Your code here
    pass

4 test cases · run your code against them in the editor