poissonp

double poissonp(int x, double l);

Returns the value of the Poisson random variable distribution function with mean l at the value x.

Parameters:
xCritical point.
lMean

Returns:
P(X ≤ x | l)

Errors:
NUM_ERRROR is raised if l ≤ 0

Usage:
double p = poissonp(5, 0.75)

Header:
#include "discdist.h"