R/pgev2.R

In FAdist: Distributions that are Sometimes Used in Hydrology

# extended version supporting shape == 0 and vectorized arguments

pgev2 <-
  function(p,shape=1,scale=1,location=0,lower.tail=TRUE,log.p=FALSE)
  {
    if(log.p) p <- exp(p)
    if(!lower.tail) p <- 1 - p

    xF <- with(expand.args(p, shape, scale, location),
               ifelse(shape == 0,
                      location - scale * log(-log(p)),
                      location + scale/shape * ((-log(p))^(-shape)-1)
               )
    )
    return(xF)
  }