Re: RREF (row reduce echelon form)

[Francesco Potorti`]

   I seem to recall several years ago there was an octave command or function
   "RREF" (row reduce echelon form), for whatever version of Octave
   corresponded to Debian 1.2 or 1.3.  Returning, I can't find "RREF".  If
   I'm just not seeing it, please tell me where to look, or how to setup.
   
   If it's not part of Octave, is there somewhere fellow users share this
   kind of code, so I don't have to reinvent the wheel?

I have a couple in my octave mail archive.  Here is one:

 Date: Tue, 16 May 2000 08:46:52 +0200 (SAST)
 From: Dirk Laurie <address@hidden>
 Subject: Re: Matlab rref equivalent?
 In-reply-to: <address@hidden>
  from <Stéfan van der address@hidden>
 To: address@hidden (Stéfan van der Walt)
 Cc: address@hidden

 [...]
 function [R,k]=rref(A,tol)
 % reduced row echelon form
 [m,n]=size(A); p=max(m,n);
 if nargin<2, tol=p*eps*norm(A,inf); end
   % pad matrix with zeros to make it square
 if m~=n, A(p,p)=0; end
 [L,U,P]=lu(A);
 k=find(abs(diag(U))>tol);
 R=U(k,k)\U(k,:);
   % remove added columns if any, add correct number of zero rows
 if n<p, R(:,n+1:p)=[]; end
 if length(k)<m, R(m,n)=0; end
 endfunction                     

 Dirk



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