scipy.special.pdtrc — SciPy v1.15.2 Manual (original) (raw)
scipy.special.pdtrc(k, m, out=None) = <ufunc 'pdtrc'>#
Poisson survival function
Returns the sum of the terms from k+1 to infinity of the Poisson distribution: sum(exp(-m) * m**j / j!, j=k+1..inf) = gammainc( k+1, m). Arguments must both be non-negative doubles.
Parameters:
karray_like
Number of occurrences (nonnegative, real)
marray_like
Shape parameter (nonnegative, real)
outndarray, optional
Optional output array for the function results
Returns:
scalar or ndarray
Values of the Poisson survival function
See also
Poisson cumulative distribution function
inverse of pdtr with respect to k
inverse of pdtr with respect to m
Examples
import numpy as np import scipy.special as sc
It is a survival function, so it decreases to 0 monotonically as k goes to infinity.
k = np.array([1, 10, 100, np.inf]) sc.pdtrc(k, 1) array([2.64241118e-001, 1.00477664e-008, 3.94147589e-161, 0.00000000e+000])
It can be expressed in terms of the lower incomplete gamma function gammainc.
sc.gammainc(k + 1, 1) array([2.64241118e-001, 1.00477664e-008, 3.94147589e-161, 0.00000000e+000])