R/Awght2Omega.R

In LatticeKrig: Multi-Resolution Kriging Based on Markov Random Fields

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# LatticeKrig is a package for analysis of spatial data written for
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omega2Awght<- function( omega, LKinfo){
  # NOTE: typically in 2D the paremeter used is
  #  kappa where  a.wght=  4 + kappa^2
  #  omega = log(kappa)
  #
  # for a rectangle this should be:
  #  Awght <- 4 +  exp( omega)^2
  # in general  a.wght =  2*dim + exp( dim*omega)
  #
  xDimension<- dim(LKinfo$x)[2]
  Awght<- LKinfo$floorAwght + exp( omega * xDimension )
  return( Awght )
}

Awght2Omega<- function( Awght, LKinfo){
  # for a rectangle this should be:
  #  Awght <- 4 +  exp( omega)^2
  # omega  <- log(  Awght - 4)/2
  if( any(Awght <= LKinfo$floorAwght) ){
    stop(paste("Awght is less than or equal to (lower limit) " ,
               LKinfo$floorAwght) )
  }
  xDimension<- dim(LKinfo$x)[2]
  omega<-  log(Awght - LKinfo$floorAwght)/xDimension
  return( omega )
}