Manuals/calci/GAMMAINV

GAMMAINV(prob,alpha,beta)

• Where 'prob' is the probability value associated with gamma distribution
• 'Alpha'& 'beta' are the values of the shape and rate parameters

Description

• This function gives the inverse value of cumulative gamma probability distribution.
• This distribution is the continuous probability distribution on the positive real line and it is of the reciprocal of a variable distributed according to the gamma distribution with two parameters α&ß.
• It is used in Bayesian statistics.
• In $GAMMAINV(prob,alpha,beta)$ , prob is the probability value associated with gamma distribution,alpha is called shape parameter and beta is the rate parameter of the distribution.
• .If GAMMADIST(x,alpha,beta,TRUE)=prob, then GAMMAINV(prob,alpha,beta,)=x.
• GAMMAINV using the iterating method to find the value of x.suppose the iteration has not converged after 100 searches, then the function gives the error result.
• This function will give the error result when

1. Any one of the arguments are nonnumeric
2. alpha or beta<=0
3. prob<0 or prob>1

Examples

1. GAMMAINV(0.65189,2,5)=11.1335534510
2. GAMMAINV(0.006867292,5,7)=8.155481331GAMMAINV(0.1543869,9,3)=18.0467153645
3. GAMMAINV(1,9,3)=82.51739521528073(CALCI)=119.4248486(EXCEL)
4. GAMMAINV(1.1,9,3)=NAN, because prob>1

See Also

• GAMMADIST
• GAMMALN

References

Gamma Distribution