## Copyright (C) 1995, 1996, 1997  Kurt Hornik
## 
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
## 
## This program is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
## General Public License for more details. 
## 
## You should have received a copy of the GNU General Public License
## along with this file.  If not, write to the Free Software Foundation,
## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

## usage:  dmult (a, B)
##
## If a is a vector of length rows (B), return diag (a) * B (but
## computed much more efficiently).
  
## Author:  KH <Kurt.Hornik@ci.tuwien.ac.at>
## Description:  Rescale the rows of a matrix
  
function M = dmult (a, B)
  
  if (nargin != 2)
    usage ("dmult (a, B)");
  endif
  
  s = size (a);
  if ((min (s) > 1) || (max (s) != rows (B)))
    error ("dmult:  a must be a vector of length rows (B)");
  endif
  
  M = (reshape (a, max (s), 1) * ones (1, columns (B))) .* B;
  
endfunction
