scipy.special.pdtrik#

scipy.special.pdtrik(p, m, out=None) = <ufunc 'pdtrik'>#

Inverse to pdtr vs k.

Parameters:
parray_like

Probability

marray_like

Shape parameter (nonnegative, real)

outndarray, optional

Optional output array for the function results

Returns:
scalar or ndarray

The number of occurrences k such that pdtr(k, m) = p

See also

pdtr

Poisson cumulative distribution function

pdtrc

Poisson survival function

pdtri

inverse of pdtr with respect to m

Notes

This function relies on the gamma_q_inva function from the Boost Math C++ library [1].

References

[1]

The Boost Developers. “Boost C++ Libraries”. https://www.boost.org/.

Examples

>>> import scipy.special as sc

Compute the CDF for several values of k:

>>> k = [1, 2, 3]
>>> p = sc.pdtr(k, 2)
>>> p
array([0.40600585, 0.67667642, 0.85712346])

Compute the inverse. We recover the values of k, as expected:

>>> sc.pdtrik(p, 2)
array([1., 2., 3.])
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