## Multiply matrix by a vector
## vector can be same length as # columns in a, or can be longer,
## in which case b[kint] is added to a * b[s:length(b)], s=length(b)-ncol(a)+1
## F. Harrell 17 Oct90
## Mod         5 Jul91 - is.vector -> !is.matrix
##            16 Oct91 - as.matrix -> matrix(,nrow=1)
##            29 Oct91 - allow b to be arbitrarily longer than ncol(a), use b(1)
##            13 Nov91 - matrix(,nrow=1) -> matrix(,ncol=1)
##            14 Nov91 - changed to nrow=1 if length(b)>1, ncol=1 otherwise
##            25 Mar93 - changed to use %*%
##            13 Sep93 - added kint parameter

matxv <- function(a, b, kint=1)
{
  if(!is.matrix(a)) {
    if(length(b)==1)
      a <- matrix(a, ncol=1) 
    else
      a <- matrix(a, nrow=1)
  }

  nc <- dim(a)[2]
  lb <- length(b)
  if(lb<nc)
    stop(paste("columns in a (",nc,") must be <= length of b (",
               length(b),")",sep=""))

  if(nc==lb)
    drop(a %*% b)
  else
    drop(b[kint] + (a %*% b[(lb-nc+1):lb]))
}

##storage.mode(a) <- "single"
##storage.mode(b) <- "double"
##
##library.dynam(section="local", file="matxv.o")
##
##.Fortran("matxv",a,b,d[1],d[2],length(b),c=single(d[1]), NAOK=T,
##	specialsok=T)$c