Chi-Square PDF Value

Problem

Chi-square probability density with k degrees of freedom at x:

f(x) = x^(k/2 - 1) * e^(-x/2) / (2^(k/2) * Gamma(k/2)).

Return 0.0 for k <= 0 or x <= 0.

Hint

A chi-square with k degrees of freedom is Gamma(k/2, 1/2).

case 1

in: [1,1]

expected: 0.24197072451914334

case 2

in: [2,1]

expected: 0.3032653298563167

case 3

in: [4,2]

expected: 0.18393972058572117

case 4

in: [1,0]

expected: 0

Starter codePython

import math


def chi_square_pdf_value(k, x):
    # Your code here
    pass

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