# HG changeset patch
# User Jaroslav Hajek <address@hidden>
# Date 1205134657 -3600
# Node ID c1230c903a74ccd24935ba7ea4d9647820e30a01
# Parent  85da2ab0c6fd626a891fdcb9185ba2d80f96ca0e
rewrite dmult to allow scaling from right and along arbitrary dimension

diff -r 85da2ab0c6fd -r c1230c903a74 scripts/ChangeLog
--- a/scripts/ChangeLog	Fri Mar 07 20:17:54 2008 -0500
+++ b/scripts/ChangeLog	Mon Mar 10 08:37:37 2008 +0100
@@ -1,3 +1,8 @@ 2008-03-07  John W. Eaton  <address@hidden
+2008-03-10  Jaroslav Hajek <address@hidden>
+
+	* linear-algebra/dmult.m: rewrite to support scaling along arbitrary
+	dimension.
+
 2008-03-07  John W. Eaton  <address@hidden>
 
 	* plot/contourf.m: Set axes layer property to "top".
diff -r 85da2ab0c6fd -r c1230c903a74 scripts/linear-algebra/dmult.m
--- a/scripts/linear-algebra/dmult.m	Fri Mar 07 20:17:54 2008 -0500
+++ b/scripts/linear-algebra/dmult.m	Mon Mar 10 08:37:37 2008 +0100
@@ -1,5 +1,4 @@
-## Copyright (C) 1995, 1996, 1997, 1998, 2000, 2002, 2004, 2005, 2006,
-##               2007 Kurt Hornik
+## Copyright (C) 2008 VZLU Prague, a.s., Czech Republic
 ##
 ## This file is part of Octave.
 ##
@@ -18,24 +17,61 @@
 ## <http://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
-## @deftypefn {Function File} {} dmult (@var{a}, @var{b})
+## @deftypefn {Function File} address@hidden = dmult (@var{a}, @var{b})
+## @deftypefnx {Function File} address@hidden = dmult (@var{a}, @var{b}, @var{index})
+## Scales a matrix by rows or columns, or a multidimensional tensor along 
+## a specified dimension. @*
 ## If @var{a} is a vector of length @code{rows (@var{b})}, return
 ## @code{diag (@var{a}) * @var{b}} (but computed much more efficiently).
+## Similarly, if @var{b} is a vector of length @code{columns(@var{a})},
+## return @address@hidden * diag(@var{b})}. 
+##
+## If @var{b} is a multidimensional array and @var{a} a vector,
+## @var{c} will have the same shape as @var{b}, with 
+## @code{C(i,:,@dots{}) = A(i)*B(i,:,@dots{})}.
+## @*
+## If @var{a} is a multidimensional array and @var{b} a vector,
+## @var{c} will have the same shape as @var{a}, with 
+## @code{C(:,@dots{},i) = A(:,@dots{},i)*B(i)}.
+##
+## If @var{ind} is supplied, @var{a} should be an array and @var{b}
+## a vector of length @code{size (@var{a},index)}. The result is then
+## @code{C(:,@dots{},i,:,@dots{}) = A(:,@dots{},i,:,@dots{})*B(i)}
+## where i indexes the @var{ind}-th dimension.
 ## @end deftypefn
 
-## Author: KH <address@hidden>
-## Description: Rescale the rows of a matrix
+## Author: Jaroslav Hajek <address@hidden>
+## Description: Scale a tensor along a dimension
 
-function M = dmult (a, B)
+### Original Author: KH <address@hidden>
+### Original Description: Rescale the rows of a matrix
 
-  if (nargin != 2)
-    print_usage ();
+function M = dmult (A, B, ind)
+  if (nargin == 2)
+    if (isvector(A) && length(A) == rows(B))
+      A = A(:);
+      sb = size(B);
+      M = reshape(kron(ones(prod(sb(2:end)), 1), A), sb) .* B;
+    elseif (isvector(B) && length(B) == columns(A))
+      B = B(:);
+      sa = size(A);
+      M = reshape(kron(B, ones(prod(sa(1:end-1)), 1)), sa) .* A;
+    else
+      error ("dmult: dimensions mismatch");
+    endif
+
+  elseif (nargin == 3 && isscalar(ind))
+    if (isvector(B) && ind > 0 && ind <= ndims(A) && length(B) == size(A, ind))
+      B = B(:);
+      sa = size(A); 
+      sal = prod(sa(1:ind-1)); sat = prod(sa(ind+1:end));
+      S = kron(ones(sat, 1), kron(B, ones(sal, 1)));
+      M = reshape(S, sa) .* A;
+    else
+      error ("dmult: dimensions mismatch or index out of range")
+    endif
+  else
+    print_usage();
   endif
- if (! isvector (a))
-    error ("dmult: a must be a vector of length rows (B)");
-  endif
-  a = a(:);
-  sb = size (B);
-  sb(1) = 1;
-  M = repmat (a(:), sb) .* B;
+
 endfunction