#####
## A function to get all permutations on numElem elements.
## There is nothing sophisticated about this. Thus, it
## is rather slow. Also, because of how the permutations
## are stored, the upper limit depends on your machine.
##
## Use:
##   getPermutations(17)

getPermutations <- function(numElem) {
  perm=matrix(NA,ncol=numElem,nrow=2^numElem)
  for(x in 0:(2^numElem-1) ) {
    mm = numElem-1
    dd = paste(rev(as.integer(intToBits(x))), collapse="")
    nn = nchar(dd)
    st = substring(dd, nn-mm,nn)
    perm[(x+1),] = as.numeric(unlist(strsplit(st,split="")))
  }
return(perm)
}