#' @name SZMW
#'
#' @title
#' The Sarhan and Zaindins Modified Weibull Distribution
#'
#' @description
#' Density, distribution function, quantile function,
#' random generation and hazard function for Sarhan and Zaindins modified weibull distribution with
#' parameters \code{mu}, \code{sigma} and \code{nu}.
#'
#' @param x,q vector of quantiles.
#' @param p vector of probabilities.
#' @param n number of observations.
#' @param mu parameter one.
#' @param sigma parameter two.
#' @param nu parameter three.
#' @param log,log.p logical; if TRUE, probabilities p are given as log(p).
#' @param lower.tail logical; if TRUE (default), probabilities are
#' P[X <= x], otherwise, P[X > x].
#'
#' @details
#' The Sarhan and Zaindins modified weibull with parameters \code{mu},
#' \code{sigma} and \code{nu} has density given by
#'
#' f(x)=(mu+sigma*nu*x^(nu-1))*exp(-mu*x-sigma*x^nu)
#'
#' for x>0.
#'
#' @return
#' \code{dSZMW} gives the density, \code{pSZMW} gives the distribution
#' function, \code{qSZMW} gives the quantile function, \code{rSZMW}
#' generates random deviates and \code{hSZMW} gives the hazard function.
#'
#' @export
#' @examples
#'
#' ## The probability density function
#' curve(dSZMW(x, mu = 2, sigma = 1.5, nu = 0.2), from = 0, to = 2, ylim = c(0, 1.7), col = "red", las = 1, ylab = "The probability density function")
#'
#' ## The cumulative distribution and the Reliability function
#' par(mfrow = c(1, 2))
#' curve(pSZMW(x, mu = 2, sigma = 1.5, nu = 0.2), from = 0, to = 2, ylim = c(0, 1), col = "red", las = 1, ylab = "The cumulative distribution function")
#' curve(pSZMW(x, mu = 2, sigma = 1.5, nu = 0.2, lower.tail = FALSE), from = 0, to = 2, ylim = c(0, 1), col = "red", las = 1, ylab = "The Reliability function")
#'
#' ## The quantile function
#' p <- seq(from = 0, to = 0.99999, length.out = 100)
#' plot(x = qSZMW(p = p, mu = 2, sigma = 1.5, nu = 0.2), y = p, xlab = "Quantile", las = 1, ylab = "Probability")
#' curve(pSZMW(x, mu = 2, sigma = 1.5, nu = 0.2), from = 0, add = TRUE, col = "red")
#'
#' ## The random function
#' hist(rSZMW(n = 1000, mu = 2, sigma = 1.5, nu = 0.2), freq = FALSE, xlab = "x", las = 1, main = "")
#' curve(dSZMW(x, mu = 2, sigma = 1.5, nu = 0.2), from = 0, add = TRUE, col = "red")
#'
#' ## The Hazard function
#' curve(hSZMW(x, mu = 2, sigma = 1.5, nu = 0.2), from = 0, to = 3, ylim = c(0, 8), col = "red", ylab = "The hazard function", las = 1)
#'
SZMW <- function (mu.link = "log", sigma.link = "log", nu.link = "log")
{
mstats <- checklink("mu.link", "Sarhan and Zaindins Modified Weibull", substitute(mu.link), c("log", "own"))
dstats <- checklink("sigma.link", "Sarhan and Zaindins Modified Weibull", substitute(sigma.link), c("log", "own"))
vstats <- checklink("nu.link", "Sarhan and Zaindins Modified Weibull", substitute(nu.link), c("log", "own"))
structure(list(family = c("SZMW", "Sarhan and Zaindins Modified Weibull"),
parameters = list(mu = TRUE, sigma = TRUE, nu = TRUE),
nopar = 3,
type = "Continuous",
mu.link = as.character(substitute(mu.link)),
sigma.link = as.character(substitute(sigma.link)),
nu.link = as.character(substitute(nu.link)),
mu.linkfun = mstats$linkfun,
sigma.linkfun = dstats$linkfun,
nu.linkfun = vstats$linkfun,
mu.linkinv = mstats$linkinv,
sigma.linkinv = dstats$linkinv,
nu.linkinv = vstats$linkinv,
mu.dr = mstats$mu.eta,
sigma.dr = dstats$mu.eta,
nu.dr = vstats$mu.eta,
dldm = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dm <- 1
dldm <- (1/exp1) * dexp1dm -y
dldm
},
d2ldm2 = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dm <- 1
d2ldm2 <- -(-((dexp1dm)^2/exp1 ^2))^2
d2ldm2
},
dldd = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dd <- nu*y^(nu-1)
dldd <-(1/exp1) * dexp1dd - y^nu
dldd
},
d2ldd2 = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dd <- nu*y^(nu-1)
d2ldd2 <- -(-((dexp1dd)^2/exp1^2)-y^nu*log(y))^2
d2ldd2
},
dldv = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dv <- sigma * y^(nu-1)*(1+nu*log(y))
dldv <- (1/exp1)*dexp1dv-sigma*y^nu*log(y)
dldv
},
d2ldv2 = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dv <- sigma * y^(nu-1)*(1+nu*log(y))
d2exp1dv2 <- sigma*y^(nu-1)*log(y)*(nu*log(y)+2)
d2ldv2 <- ((exp1*d2exp1dv2-dexp1dv)/(exp1^2))-sigma*y^nu*(log(y))^2
d2ldv2
},
d2ldmdd = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dm <- 1
dexp1dd <- nu*y^(nu-1)
d2ldmdd <- (dexp1dm*dexp1dd)/exp1^2
d2ldmdd
},
d2ldmdv = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dm <- 1
dexp1dv <- sigma * y^(nu-1)*(1+nu*log(y))
d2ldmdv <- (dexp1dm*dexp1dv)/exp1^2
d2ldmdv
},
d2ldddv = function(y, mu, sigma, nu) {
exp1 <- mu + sigma*nu * y ^ (nu-1)
dexp1dd <- nu*y^(nu-1)
dexp1dv <- sigma * y^(nu-1)*(1+nu*log(y))
d2exp1dddv <- y^(nu-1)*(1+nu*log(y))
d2ldddv <- ((exp1*d2exp1dddv-dexp1dd*dexp1dv)/exp1^2)-y^nu*log(y)
d2ldddv
},
G.dev.incr = function(y, mu, sigma, nu, ...) -2*dSZMW(y, mu, sigma, nu, log = TRUE),
rqres = expression(rqres(pfun = "pSZMW", type = "Continuous", y = y, mu = mu, sigma = sigma, nu = nu)),
mu.initial = expression( mu <- rep(0.5, length(y)) ),
sigma.initial = expression( sigma <- rep(0.5, length(y)) ),
nu.initial = expression( nu <- rep(0.5, length(y)) ),
mu.valid = function(mu) all(mu > 0),
sigma.valid = function(sigma) all(sigma > 0),
nu.valid = function(nu) all(nu > 0),
y.valid = function(y) all(y > 0)
),
class = c("gamlss.family", "family"))
}
#' @export
#' @rdname SZMW
dSZMW<-function(x,mu,sigma,nu, log = FALSE){
if (any(x<0))
stop(paste("x must be positive", "\n", ""))
if (any(mu<=0 ))
stop(paste("mu must be positive", "\n", ""))
if (any(sigma<=0))
stop(paste("sigma must be positive", "\n", ""))
if (any(nu<=0))
stop(paste("nu must be positive", "\n", ""))
loglik<- log(mu + sigma*nu*x^(nu-1)) - mu*x - sigma*x^nu
if (log == FALSE)
density<- exp(loglik)
else
density <- loglik
return(density)
}
#' @export
#' @rdname SZMW
pSZMW <- function(q,mu,sigma,nu, lower.tail=TRUE, log.p = FALSE){
if (any(q<0))
stop(paste("q must be positive", "\n", ""))
if (any(mu<=0 ))
stop(paste("mu must be positive", "\n", ""))
if (any(sigma<=0))
stop(paste("sigma must be positive", "\n", ""))
if (any(nu<=0))
stop(paste("nu must be positive", "\n", ""))
cdf <- 1- exp(-mu*q -sigma*(q^nu))
if (lower.tail == TRUE)
cdf <- cdf
else cdf <- 1 - cdf
if (log.p == FALSE)
cdf <- cdf
else cdf <- log(cdf)
cdf
}
#' @export
#' @rdname SZMW
qSZMW <- function(p, mu,sigma,nu, lower.tail = TRUE, log.p = FALSE) {
if (any(mu<=0 ))
stop(paste("mu must be positive", "\n", ""))
if (any(sigma<=0))
stop(paste("sigma must be positive", "\n", ""))
if (any(nu<=0))
stop(paste("nu must be positive", "\n", ""))
if (log.p == TRUE)
p <- exp(p)
else p <- p
if (lower.tail == TRUE)
p <- p
else p <- 1 - p
if (any(p < 0) | any(p > 1))
stop(paste("p must be between 0 and 1", "\n", ""))
fda <- function(x,mu,sigma,nu){
1- exp(-mu*x - sigma*(x^nu))
}
fda1 <- function(x, mu,sigma,nu, p) {fda(x, mu,sigma,nu) - p}
r_de_la_funcion <- function(mu,sigma,nu, p) {
uniroot(fda1, interval=c(0,1e+06), mu,sigma,nu, p)$root
}
r_de_la_funcion <- Vectorize(r_de_la_funcion)
q <- r_de_la_funcion(mu,sigma,nu, p)
q
}
#' @export
#' @rdname SZMW
rSZMW<- function(n,mu,sigma,nu){
if (any(mu<=0 ))
stop(paste("mu must be positive", "\n", ""))
if (any(sigma<=0))
stop(paste("sigma must be positive", "\n", ""))
if (any(nu<=0))
stop(paste("nu must be positive", "\n", ""))
n <- ceiling(n)
p <- runif(n)
r <- qSZMW(p, mu,sigma,nu)
r
}
#' @export
#' @rdname SZMW
hSZMW<-function(x,mu,sigma,nu){
if (any(x<0))
stop(paste("x must be positive", "\n", ""))
if (any(mu<=0 ))
stop(paste("mu must be positive", "\n", ""))
if (any(sigma<=0))
stop(paste("sigma must be positive", "\n", ""))
if (any(nu<=0))
stop(paste("nu must be positive", "\n", ""))
h <- dSZMW(x,mu,sigma,nu, log = FALSE)/pSZMW(q=x,mu,sigma,nu, lower.tail=FALSE, log.p = FALSE)
h
}
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