--- /dev/null
+## Copyright (C) 2010 Mark Borgerding <mark@borgerding.net>
+##
+## 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 3 of the License, 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 program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{outdata} =} helscanintrlv (@var{data}, @var{nrows}, @var{ncols},@var{Nshift})
+## @var{nrows}-by-@var{ncols}.
+## @seealso{helscandeintrlv}
+## @end deftypefn
+
+function outdata = helscanintrlv(data,Nrows,Ncols,Nshift)
+
+ if(nargin ~= 4 )
+ error('usage : interlvd = helscanintrlv(data,Nrows,Ncols,Nshift)');
+ end
+
+ if(~isscalar(Nrows) || ~isscalar(Ncols))
+ error("Nrows and Ncols must be integers");
+ end
+
+ if( Nrows ~= floor(Nrows)|| Ncols ~= floor(Ncols))
+ error("Nrows and Ncols must be integers");
+ end
+
+ didTranspose=0;
+ if ( isvector(data) && columns(data) > rows(data) )
+ data = data.';
+ didTranspose=1;
+ end
+
+ s = size(data);
+
+ if size(data,1) ~= Nrows*Ncols
+ error("The length of data must be equals to Ncols*Nrows");
+ end
+
+ # create the interleaving indices
+ idx0 = 0:Nrows*Ncols-1;
+ idxMod = rem(idx0,Ncols);
+ idxFlr = idx0 - idxMod;
+ inds = 1+rem(idxFlr + idxMod * Ncols * Nshift + idxMod,Nrows*Ncols);
+
+ # for each column
+ for k = 1:s(2)
+ outdata(:,k) = data(inds,k);
+ end
+
+ if didTranspose
+ outdata = outdata.';
+ end