function [start,finish]=regexp(str,expr)
// Match regular expressions in strings.
// str - string to be processed.
// expr - regular expression to be identified in str
// start - index to start of each matching expr in str.
// finish - index to end of each matching expr in str.
// Description
// regexp idetifies the start and finish of each matching
// regular expression in a string. 
// regexp requires that perl is installed and available through the path. 
//
// Unforturnately regexp.sci has not been adapted to work in an 
// Windows/MSDOS environment, but this only requires minor 
// modifications to the source code.
//
// Examples:
// str='bat cat can car coat court cut ct caoueaouat';
// pat = 'c[aeiou]+t';
// [s,f]=regexp(str,pat)
// [s,f]=regexp('regexp helps you relax','\w*x\w*')

// Copyright (C) 2003 Torbjørn Pettersen.
//	$Id: regexp.sci,v 1.3 2003/11/04 18:12:09 top Exp $	

// 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 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, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

if MSDOS, 
  x_message(['regexp.sci only works in linux/unix environments currently',...
	  'You only need to modify the code slightly to work under Windows.'])
end

// A nice selfexplaining perl program does the jobb :-)
pl = "...
    $_=shift; $e=shift; ...
    while($_) { ...
    if (/($e)/) { ... 
	push(@tok,$1); ...
	push(@st,index($_,$1)+1); ...
	($foo,$_)=split($e,$_,2); ...
      } else { $_='''';}; ...
    }; ...
    @fin=@st; @fin[0]=@fin[0]+length(@tok[0])-1; ...
    for $i (1..$#st) { ...
       @st[$i]=@st[$i-1]-1+@st[$i]+length(@tok[$i-1]); ...
       @fin[$i]=@st[$i]+length(@tok[$i])-1; ...
    }; ...
    print ""{["".join('';'',@st).""],["".join('';'',@fin).""]}\n"";";

u=file('open',TMPDIR+'/regexp.pl','unknown'); 
write(u,pl);				// write down the perl program 
file('close',u);

// Run perl program and evaluate the output from the program.
res=evstr(...
    unix_g("perl "+TMPDIR+"/regexp.pl "+sprintf(' ''%s'' ''%s''',str,expr)));

start=res(:,1); 
finish=res(:,2);