lmomco (version 2.2.4)

quagam: Quantile Function of the Gamma Distribution

Description

This function computes the quantiles of the Gamma distribution given parameters ($\alpha$ and $\beta$) computed by pargam. The quantile function has no explicit form. See the qgamma function of R and cdfgam. The parameters have the following interpretations: $\alpha$ is a shape parameter and $\beta$ is a scale parameter in the R syntax of the qgamma function.

Usage

quagam(f, para, paracheck=TRUE)

Arguments

f

Nonexceedance probability ($0 \le F \le 1$).

para

The parameters from pargam or vec2par.

paracheck

A logical controlling whether the parameters are checked for validity. Overriding of this check might be extremely important and needed for use of the quantile function in the context of TL-moments with nonzero trimming.

Value

Quantile value for nonexceedance probability $F$.

References

Hosking, J.R.M., 1990, L-moments---Analysis and estimation of distributions using linear combinations of order statistics: Journal of the Royal Statistical Society, Series B, v. 52, pp. 105--124.

Hosking, J.R.M., 1996, FORTRAN routines for use with the method of L-moments: Version 3, IBM Research Report RC20525, T.J. Watson Research Center, Yorktown Heights, New York.

Hosking, J.R.M., and Wallis, J.R., 1997, Regional frequency analysis---An approach based on L-moments: Cambridge University Press.

See Also

cdfgam, pdfgam, lmomgam, pargam

Examples

  lmr <- lmoms(c(123,34,4,654,37,78))
  g <- pargam(lmr)
  quagam(0.5,g)
## Not run: 
#   # generate 50 random samples from this fitted parent
#   Qsim <- rlmomco(5000,g)
#   # compute the apparent gamma parameter for this parent
#   gsim <- pargam(lmoms(Qsim))
# ## End(Not run)