\name{RMsign}
\alias{RMsign}
\alias{RRsign}
\title{Random sign}
\description{
  \command{RMsign} defines a random sign. It can be used as part of the
  model definition of a Poisson field. 

 }
\usage{
RMsign(phi, p)
}

\arguments{
 \item{phi}{shape function of class \code{\link[=RMmodel-class]{RMmodel}}.}
 \item{p}{probability of keeping the sign}
}

\details{
  \command{RMsign} changes the sign of the shape function \code{phi}
  with probability \code{1-p} and keeps it otherwise.
}
 
\value{
 \command{\link{RMsign}} returns an object of class \code{\link[=RMmodel-class]{RMmodel}}

}

\note{
  Random univariate or multivariate objects are
  usually start with \code{RR} not with \code{RM}.
  This is an exception here, as it operates on shape functions.
}

\author{Martin Schlather, \email{schlather@math.uni-mannheim.de}
}
\seealso{
  \command{\link{RMmodel}}
  \link{RR}.

 }


\keyword{spatial}
\keyword{models}




\examples{
RFoptions(seed=0) ## *ANY* simulation will have the random seed 0; set
##                   RFoptions(seed=NA) to make them all random again
\dontshow{StartExample()}
model <- RPpoisson(RMsign(RMtent(), p=0.8))
x <- seq(0, 10, 0.02)
plot(RFsimulate(model, x=x))
\dontshow{FinalizeExample()}
}