Re: strange problem

[Gerald Ebberink]

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Most probably they have the same problem I have,
when you are stuck with a question you take it home. you think you have
a solution logon to the network en try it..

:)

THOMAS Paul Richard wrote:
| Gerald,
|
| I am glad that the function did it for you.  As several of the respondents
| said, this is a result of limitations in floating point arithmetic.
|
| Not only is the response time of this list good but you should check
out the
| times of the replies and the locations of some of our friends on this
list.
| I sort of wonder if they have homes to go to?
|
| Paul
|
| -----Message d'origine-----
| De : Gerald Ebberink [mailto:address@hidden
| Envoyé : vendredi 28 novembre 2003 11:39
| À : address@hidden
| Objet : Re: strange problem
|
|
| Problem solved,
| thnx all
|
| since I don't work under windows the function gives me a nice way of
| cleaning th results after each multiplication.
|
| by the way, this list has a very low response time. Other programs have
| far worse lists.
|
| THOMAS Paul Richard wrote:
| | Dear All,
| |
| | The matrix multiplication gives zero for ans(1,1) in octave 2.1.49
(under
| | Cygwin)!  However, Matlab5 gives the same result as Gerald's.
| |
| | Compiling the expression 1-(100*-1)/100 in g++ or intel C++ give 0.  I
| would
| | conclude that this is some peculiarity of BLAS that seems to have been
| | eliminated in later versions of Octave/BLAS.
| |
| | It seems to me that Gerald's work-around might be to use
| |
| | function xout=clean(xin,prec);xout=xin.*(abs(xin)>prec);endfunction;
| |
| | so that
| |
| | a=clean([1,100;0,1]*[1,0;(-1/100),1],1E-16);
| |
| | a(1,1) yields 0
| |
| | Paul
| |
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|
|
| --
| Ing. Gerald Ebberink
| Laser Technician
|
| Kernfysisch Versneller Instituut
| Rijksuniversiteit Groningen
| Zernikelaan 25
| 9747 AA Groningen
| The Netherlands
| tel: +31 50 363 3518
| lab: +31 50 363 3588
| fax: +31 50 363 4003
|
|

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Version: 6.0.536 / Virus Database: 331 - Release Date: 03/11/03




- -------------------------------------------------------------
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
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- --
Ing. Gerald Ebberink
Laser Technician

Kernfysisch Versneller Instituut
Rijksuniversiteit Groningen
Zernikelaan 25
9747 AA Groningen
The Netherlands
tel: +31 50 363 3518
lab: +31 50 363 3588
fax: +31 50 363 4003


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-------------------------------------------------------------
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
-------------------------------------------------------------