diff --git a/R/cfGAL.R b/R/cfGAL.R
index d6ef641..43d2c13 100644
--- a/R/cfGAL.R
+++ b/R/cfGAL.R
@@ -15,6 +15,7 @@
 #' @author Francois Pelletier
 cfGAL <- function(u,param,type="mu",log=FALSE)
 {
+	testparGAL(param,type,log)
 	if(log)
 	{
 		if(type=="mu")
diff --git a/R/changetypeGAL.R b/R/changetypeGAL.R
index 7ba6131..fbbde25 100644
--- a/R/changetypeGAL.R
+++ b/R/changetypeGAL.R
@@ -15,6 +15,7 @@
 #' @author Francois Pelletier
 changetypeGAL <- function(param,type="mu",target="kappa",log=FALSE)
 {
+	testparGAL(param,type,log)
 	if(log)
 	{
 		if(type=="mu" && target=="kappa")
diff --git a/R/dGAL.r b/R/dGAL.r
index eecd280..03201f5 100644
--- a/R/dGAL.r
+++ b/R/dGAL.r
@@ -8,6 +8,7 @@
 #' @author Francois Pelletier
 dGAL <- function(x,param,type="mu",log=FALSE)
 {
+	testparGAL(param,type,log)
 	if(log)
 	{
 		if(type=="mu")
diff --git a/R/fgmGAL.R b/R/fgmGAL.R
index 0d4eb94..df1522a 100644
--- a/R/fgmGAL.R
+++ b/R/fgmGAL.R
@@ -15,6 +15,7 @@
 #' @author Francois Pelletier
 mgfGAL <- function(u,param,type="mu",log=FALSE)
 {
+	testparGAL(param,type,log)
 	if(log)
 	{
 		if(type=="mu")
diff --git a/R/rGAL.R b/R/rGAL.R
new file mode 100644
index 0000000..e530e85
--- /dev/null
+++ b/R/rGAL.R
@@ -0,0 +1,52 @@
+# Random number generator for the GAL distribution
+# 
+# Author: Francois Pelletier
+#
+# LGPL 3.0
+###############################################################################
+
+
+#' Random number generator for the GAL distribution
+#' @param n number of observations
+#' @param param Parameter vector
+#' @param type Choose between "mu" or "kappa" parametrization
+#' @param log Logical for log-parameters 
+#' @return A vector of random numbers
+#' 
+#' @author Francois Pelletier
+rGAL <- function(n,param,type="mu",log=FALSE)
+{
+	testparGAL(param,type,log)
+	if(log)
+	{
+		if(type=="mu")
+		{
+			rGAL(n,changetypeGAL(param,type="mu",target="kappa"),type="kappa",log=log)
+		}
+		if(type=="kappa")
+		{
+			# simulation de deux variables gamma
+			rgamma1 <- rgamma(n, shape = exp(param[4]), scale = 1/exp(param[3]))
+			rgamma2 <- rgamma(n, shape = exp(param[4]), scale = exp(param[3]))
+			
+			# simulation de la variable GAL
+			exp(param[1]) + exp(param[2])/sqrt(2)*(rgamma1 - rgamma2)			
+		}
+	}
+	else
+	{
+		if(type=="mu")
+		{
+			rGAL(n,changetypeGAL(param,type="mu",target="kappa"),type="kappa",log=log)
+		}
+		if(type=="kappa")
+		{
+			# simulation de deux variables gamma
+			rgamma1 <- rgamma(n, shape = param[4], scale = 1/param[3])
+			rgamma2 <- rgamma(n, shape = param[4], scale = param[3])
+			
+			# simulation de la variable GAL
+			param[1] + param[2]/sqrt(2)*(rgamma1 - rgamma2)
+		}
+	}
+}
diff --git a/R/testparGAL.R b/R/testparGAL.R
new file mode 100644
index 0000000..3065434
--- /dev/null
+++ b/R/testparGAL.R
@@ -0,0 +1,53 @@
+# Check for the validity of a parameter vector. Stop at error.
+# 
+# Author: Francois Pelletier
+#
+# LGPL 3.0
+###############################################################################
+
+
+#' Check for the validity of a parameter vector. Stop at error.
+#' @param param Parameter vector
+#' @param type Choose between "mu" or "kappa" parametrization
+#' @param log Logical for log-parameters 
+#' @return logical
+#' 
+#' @author Francois Pelletier
+testparGAL <- function(param,type="mu",log=FALSE)
+{
+	if(log)
+	{
+		if(type=="mu")
+		{
+			if(exp(param[2])<=0)
+				stop("param 2 must be positive")
+			if(exp(param[4])<=0)
+				stop("param 4 must be positive")
+		}
+		if(type=="kappa")
+		{
+			if(exp(param[2])<=0)
+				stop("param 2 must be positive")
+			if(exp(param[4])<=0)
+				stop("param 4 must be positive")
+		}
+	}
+	else
+	{
+		if(type=="mu")
+		{
+			if(param[2]<=0)
+				stop("param 2 must be positive")
+			if(param[4]<=0)
+				stop("param 4 must be positive")
+		}
+		if(type=="kappa")
+		{
+			if(param[2]<=0)
+				stop("param 2 must be positive")
+			if(param[4]<=0)
+				stop("param 4 must be positive")	
+		}		
+	}
+	TRUE
+}
diff --git a/man/rGAL.Rd b/man/rGAL.Rd
new file mode 100644
index 0000000..cfd2211
--- /dev/null
+++ b/man/rGAL.Rd
@@ -0,0 +1,26 @@
+\name{rGAL}
+\alias{rGAL}
+\title{Random number generator for the GAL distribution}
+\usage{
+rGAL(n, param, type = "mu", log = FALSE)
+}
+\arguments{
+  \item{n}{number of observations}
+
+  \item{param}{Parameter vector}
+
+  \item{type}{Choose between "mu" or "kappa"
+  parametrization}
+
+  \item{log}{Logical for log-parameters}
+}
+\value{
+A vector of random numbers
+}
+\description{
+Random number generator for the GAL distribution
+}
+\author{
+Francois Pelletier
+}
+
diff --git a/man/testparGAL.Rd b/man/testparGAL.Rd
new file mode 100644
index 0000000..7abde38
--- /dev/null
+++ b/man/testparGAL.Rd
@@ -0,0 +1,25 @@
+\name{testparGAL}
+\alias{testparGAL}
+\title{Check for the validity of a parameter vector. Stop at error.}
+\usage{
+testparGAL(param, type = "mu", log = FALSE)
+}
+\arguments{
+  \item{param}{Parameter vector}
+
+  \item{type}{Choose between "mu" or "kappa"
+  parametrization}
+
+  \item{log}{Logical for log-parameters}
+}
+\value{
+logical
+}
+\description{
+Check for the validity of a parameter vector. Stop at
+error.
+}
+\author{
+Francois Pelletier
+}
+