Armijo Condition Check

Problem

Check the Armijo sufficient-decrease condition for a step of size step along the descent direction -grad. Return True when f_new <= f_current - c * step * grad ** 2, and False otherwise. Here grad is the current gradient component along that direction.

Hint

Armijo compares the new value against the tangent line with slope -grad squared.

Test cases

case 1

in: [1,0.5,1,1,0.1]

expected: true

case 2

in: [1,0.85,1,1,0.1]

expected: true

case 3

in: [4,3,2,0.5,0.25]

expected: true

case 4

in: [0,0.001,0,1,0.1]

expected: false

Starter codePython

def armijo_condition(f_current, f_new, grad, step, c):
    # Your code here
    pass

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