# mars.tensor.special.gammaincinv#

mars.tensor.special.gammaincinv(a, b, **kwargs)[source]#

Inverse to the lower incomplete gamma function with respect to x.

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
• a (array_like) – Positive parameter

• y (array_like) – Parameter between 0 and 1, inclusive

Returns

Values of the inverse of the lower incomplete gamma function

Return type

scalar or ndarray

See also

gammainc

regularized lower incomplete gamma function

gammaincc

regularized upper incomplete gamma function

gammainccinv

inverse of the regualizred upper incomplete gamma function with respect to x

References

dlmf

NIST Digital Library of Mathematical Functions https://dlmf.nist.gov/8.2#E4