`scipy.stats._continuous_distns:ncx2_gen`

source: /scipy/stats/_continuous_distns.py :7782

Signature

   class     ncx2_gen (    momtype    =  1   ,    a    =  None   ,    b    =  None   ,    xtol    =  1e-14   ,    badvalue    =  None   ,    name    =  None   ,    longname    =  None   ,    shapes    =  None   ,    seed    =  None     )

Members

Summary

A non-central chi-squared continuous random variable.

Extended Summary

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Notes

The probability density function for ncx2 is:

f (x, k, λ) = \frac{1}{2} exp (- (λ + x) /2) (x / λ)^{(k - 2) /4} I_{(k - 2) /2} (λ x)

for $x >= 0$ , $k > 0$ and $λ \geq 0$ . $k$ specifies the degrees of freedom (denoted df in the implementation) and $λ$ is the non-centrality parameter (denoted nc in the implementation). $I_{ν}$ denotes the modified Bessel function of first order of degree $ν$ (scipy.special.iv).

ncx2 takes df and nc as shape parameters.

This distribution uses routines from the Boost Math C++ library for the computation of the pdf, cdf, ppf, sf and isf methods. ^[1]

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Aliases

scipy.stats._continuous_distns.ncx2_gen