InverseGammaRegularized
InverseGammaRegularized[a, s] gives the inverse of the regularized incomplete gamma function.
Examples
Compute inverse:
InverseGammaRegularized[2, 0.5]
(* 1.67835 *)Verify relationship:
GammaRegularized[2, InverseGammaRegularized[2, 0.5]]
(* 0.5 *)Please visit the official Wolfram Language Reference for more details.