From help-request at octave dot org Sat Apr 15 15:54:56 2006 Subject: Re: chol? From: Joe Koski To: Marius Schamschula , Vic Norton CC: Octave Help Date: Sat, 15 Apr 2006 14:53:18 -0600 > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3227957599_24169004 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Vic, Marius, It must be the HPC version. On my home built with g95 version: octave:1> C =3D [36 24; 24 25]; octave:2> chol(C); octave:3> chol(C) ans =3D 6 4 0 3 Upper Triangular octave:4> version ans =3D 2.1.73 =20 Joe on 4/15/06 2:29 PM, Marius Schamschula at marius173 at mchsi dot com wrote: > Vic, >=20 > Is this the port from hpc.sf.net, or did you compile from source? >=20 > I have yet to get a working build of octave 2.1.73 on the Mac. >=20 > On Apr 15, 2006, at 3:16 PM, Vic Norton wrote: >=20 >> 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. >>=20 >> I start with the matrix >> =A0=A0 octave> C =3D [36 24; 24 25]; >> and do >> =A0=A0 octave> chol(C); >> After waiting for a while I get >> =A0=A0 panic: Bus error -- stopping myself... >> =A0=A0 attempting to save variables to `octave-core'... >> =A0=A0 save to `octave-core' complete >> =A0=A0 Bus error >> =A0=A0 vic$ >>=20 >> To tell you the truth I'm not sure what the Cholesky factor of C is >> supposed to be. I do know that C =3D R' * R where >> =A0=A0 R =3D [0 3; 6 4]. >> I have no problem computing another R that does this job: >> =A0=A0 octave> C =3D [36 24; 24 25]; >> =A0=A0 octave> [U, S, V] =3D svd(C); >> =A0=A0 octave> R =3D sqrt(S) * V'; >> Now >> =A0=A0 R =3D [ >> =A0 =A0 =A0 =A0 =A0 -5.8067=A0 -4.6265 >> =A0 =A0 =A0 =A0 =A0 -1.5108 =A0 1.8962 >> =A0=A0 =A0 =A0 ] >> and C =3D R' * R for this R as well. But R =3D chol(C) simply doesn't work >> for me. >>=20 >> Is anybody else having any problems with "chol" or is it just my screwed >> up system? >>=20 >> Regards, >>=20 >> Vic >=20 >=20 > =20 >=20 > Marius >=20 > -- >=20 > Marius Schamschula =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Webmaster >=20 >=20 >=20 > =A0 =A0 =A0 =A0 The Huntsville Macintosh Users Group >=20 > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 www.hmug.org >=20 >=20 >=20 > webmaster at hmug dot org=A0 =A0 marius at schamschula dot com >=20 >=20 > =20 >=20 >=20 --B_3227957599_24169004 Content-type: text/html; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Re: chol? Vic, = Marius,

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

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

   6  4
   0  3
 Upper Triangular

 octave:4> version
 ans =3D 2.1.73
 

Joe


on 4/15/06 2:29 PM, Marius Schamschula at marius173 at mchsi dot com 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
=A0=A0 octave> C =3D [36 24; 24 25];
and do
=A0=A0 octave> chol(C);
After waiting for a while I get
=A0=A0 panic: Bus error -- stopping myself...
=A0=A0 attempting to save variables to `octave-core'...
=A0=A0 save to `octave-core' complete
=A0=A0 Bus error
=A0=A0 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 =3D R' * R where
=A0=A0 R =3D [0 3; 6 4].
I have no problem computing another R that does this job:
=A0=A0 octave> C =3D [36 24; 24 25];
=A0=A0 octave> [U, S, V] =3D svd(C);
=A0=A0 octave> R =3D sqrt(S) * V';
Now
=A0=A0 R =3D [
=A0 =A0 =A0 =A0 =A0 -5.8067=A0 -4.6265
=A0 =A0 =A0 =A0 =A0 -1.5108 =A0 1.8962
=A0=A0 =A0 =A0 ]
and C =3D R' * R for this R as well. But R =3D 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 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Webmaster



=A0 =A0 =A0 =A0 The Huntsville Macintosh Users Group

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 www.hmug.org <http://w= ww.hmug.org>



webmaster at hmug dot org=A0 =A0 marius at schamschula dot com


 



 --B_3227957599_24169004-- ------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. Octave's home on the web: http://www.octave.org How to fund new projects: http://www.octave.org/funding.html Subscription information: http://www.octave.org/archive.html -------------------------------------------------------------