import math


def inverse_gamma(data, alpha=0.1, beta=0.1):
    """
    Inverse gamma distributions
    :param data: Data value
    :param alpha: alpha value
    :param beta: beta value
    :return: Inverse gamma distributiion
    """
    return (pow(beta, alpha) / math.gamma(alpha)) *\
           pow(alpha, data-1) * math.exp(-beta/data)