scipy.stats._continuous_distns:_argus_phi

Summary

Utility function for the argus distribution used in the pdf, sf and moment calculation. Note that for all x > 0: gammainc(1.5, x**2/2) = 2 * (_norm_cdf(x) - x * _norm_pdf(x) - 0.5). This can be verified directly by noting that the cdf of Gamma(1.5) can be written as erf(sqrt(x)) - 2*sqrt(x)*exp(-x)/sqrt(Pi). We use gammainc instead of the usual definition because it is more precise for small chi.