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Re: chol?


From: Joe Koski
Subject: Re: chol?
Date: Sat, 15 Apr 2006 14:53:18 -0600
User-agent: Microsoft-Entourage/11.2.3.060209

Vic, Marius,

It must be the HPC version. On my home built with g95 version:

 octave:1> C = [36 24; 24 25];
 octave:2> chol(C);
 octave:3> chol(C)
 ans =

   6  4
   0  3
 Upper Triangular

 octave:4> version
 ans = 2.1.73
 

Joe


on 4/15/06 2:29 PM, Marius Schamschula at address@hidden wrote:

Vic,

Is this the port from hpc.sf.net, or did you compile from source?

I have yet to get a working build of octave 2.1.73 on the Mac.

On Apr 15, 2006, at 3:16 PM, Vic Norton wrote:

I had thought Octave, version 2.1.73, was working fine on my iMac G5,
but now I'm not so sure. Here's my problem.

I start with the matrix
   octave> C = [36 24; 24 25];
and do
   octave> chol(C);
After waiting for a while I get
   panic: Bus error -- stopping myself...
   attempting to save variables to `octave-core'...
   save to `octave-core' complete
   Bus error
   vic$

To tell you the truth I'm not sure what the Cholesky factor of C is
supposed to be. I do know that C = R' * R where
   R = [0 3; 6 4].
I have no problem computing another R that does this job:
   octave> C = [36 24; 24 25];
   octave> [U, S, V] = svd(C);
   octave> R = sqrt(S) * V';
Now
   R = [
          -5.8067  -4.6265
          -1.5108   1.8962
       ]
and C = R' * R for this R as well. But R = chol(C) simply doesn't work
for me.

Is anybody else having any problems with "chol" or is it just my screwed
up system?

Regards,

Vic


 

Marius

--

Marius Schamschula                               Webmaster



        The Huntsville Macintosh Users Group

                    www.hmug.org <http://www.hmug.org>



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