@staticmethod
def evaluate(x, amplitude, x_0, alpha):
    'One dimensional power law model function'
    xx = (x / x_0)
    return (amplitude * (xx ** (- alpha)))
One dimensional power law model function
@staticmethod
def evaluate(x, amplitude, x_0, alpha):
    
    xx = (x / x_0)
    return (amplitude * (xx ** (- alpha)))