def poisson(x, a, b, c, d=0):
    '''
    Poisson function
    a -> height of the curve's peak
    b -> position of the center of the peak
    c ->  standard deviation 
    d -> offset
    '''
    from scipy.misc import factorial #save startup time
    lamb = 1
    X = (x/(2*c)).astype(int)
    return a * (( lamb**X/factorial(X)) * np.exp(-lamb) ) +d
def poisson ( x , a , b , c , d = 0 ) : from scipy . misc import factorial lamb = 1 X = ( x / ( 2 * c ) ) . astype ( int ) return a * ( ( lamb ** X / factorial ( X ) ) * np . exp ( - lamb ) ) + d
Poisson function
    a -> height of the curve's peak
    b -> position of the center of the peak
    c ->  standard deviation 
    d -> offset