R/qlindley.R

In matheuscastro43/finiteMix: Finite Mixture Models

qlindley <- function(p, beta, lower.tail = TRUE, log.p = FALSE){
  if(length(p) == 1){
    if(length(beta) == 1){
      if(beta > 0 && length(beta) == 1){
        if(log.p){
          p = exp(p)
        }
        if(!lower.tail){
          p = 1 - p
        }
        if(p < 0 || p > 1){
          warning("The probability must be in (0, 1) interval.")
          return(NaN)
        }
        else{
          if(p == 0){return(0)}
          else{
            if(p == 1){return(Inf)}
            else{
              U = aux = 100
              h = function(q){
                plindley(q, beta) - p
              }
              while(aux >= 0.9*U){
                U = 2*U
                aux = uniroot(h, lower = 0, upper = U)$root
              }
              return(aux)
            }
          }
        }
      }
      else stop("The parameter must be positive.")
    }else{
      k <- function(x, beta) qlindley(p, beta, lower.tail, log.p)
      mapply(k, p, beta)
    }
  }else{
    j = function(p){qlindley(p, beta, lower.tail, log.p)}
    return(sapply(p, j))
  }
}