Gamma Inverse CDF
x = distfun_gaminv ( p , a , b ) x = distfun_gaminv ( p , a , b , lowertail )
a nxm matrix of doubles, the probability
a 1x1 or nxm matrix of doubles, the shape parameter, greater or equal to zero
a 1x1 or nxm matrix of doubles, the scale parameter, greater or equal to zero
a 1x1 matrix of booleans, the tail (default lowertail=%t). If lowertail is true (the default), then considers P(X<x) otherwise P(X>x).
a 1x1 or nxm matrix of doubles, the outcome, greater or equal to zero
Computes the Gamma inverse cumulated probability distribution function.
Any scalar input argument is expanded to a matrix of doubles of the same size as the other input arguments.
Notice that b, the scale, is the inverse of the rate. Other computing languages (including R), use 1/b as the second parameter of the Gamma distribution.