scipy.special.gammaincinv — SciPy v1.15.2 Manual (original) (raw)
scipy.special.gammaincinv(a, y, out=None) = <ufunc 'gammaincinv'>#
Inverse to the regularized lower incomplete gamma function.
Given an input \(y\) between 0 and 1, returns \(x\) such that \(y = P(a, x)\). Here \(P\) is the regularized lower incomplete gamma function; see gammainc. This is well-defined because the lower incomplete gamma function is monotonic as can be seen from its definition in [dlmf].
Parameters:
aarray_like
Positive parameter
yarray_like
Parameter between 0 and 1, inclusive
outndarray, optional
Optional output array for the function values
Returns:
scalar or ndarray
Values of the inverse of the lower incomplete gamma function
See also
regularized lower incomplete gamma function
regularized upper incomplete gamma function
inverse of the regularized upper incomplete gamma function
References
Examples
import scipy.special as sc
It starts at 0 and monotonically increases to infinity.
sc.gammaincinv(0.5, [0, 0.1 ,0.5, 1]) array([0. , 0.00789539, 0.22746821, inf])
It inverts the lower incomplete gamma function.
a, x = 0.5, [0, 0.1, 0.5, 1] sc.gammainc(a, sc.gammaincinv(a, x)) array([0. , 0.1, 0.5, 1. ])
a, x = 0.5, [0, 10, 25] sc.gammaincinv(a, sc.gammainc(a, x)) array([ 0. , 10. , 25.00001465])