Re: Re: Generalized Eigenvector and Singular Value Decompositions
- To: mathgroup at christensen.Cybernetics.NET (mathgroup)
- Subject: [mg316] Re: [mg306] Re: [mg304] Generalized Eigenvector and Singular Value Decompositions
- From: onm010 at aixrs1.hrz.uni-essen.de (Dr. Stefan P. Mueller)
- Date: Mon, 12 Dec 1994 15:26:58 +0100
>
>To:rickli at aut.ee.ethz.ch (Martin Rickli)
>From:onm010 at aixrs1.hrz.uni-essen.de (Dr. Stefan P. Mueller)
>Subject:Re: [mg306] Re: [mg304] Generalized Eigenvector and Singular Value
>Decompositions
>
>> ...
>>These days I tripped over a bug in SingularValues which seams to appear
>>only in the Mac version of Mma (v2.2).
>>Try the following:
>>
>>mat = {{1, 1}, {-Sqrt[2], Sqrt[2]}};
>>
>>SingularValues[ SetPrecision[mat,19] ] (* Mac MachinePrecision *)
>>SingularValues[ SetPrecision[mat,20] ]
>>
>>This matrix shouldn't pose numerical difficulties but SingularValues fails
>>to converge if calculations are done with machine precision numbers. With
>>higher precision numbers the result is correct.
>>As I said above, this seams to appear only in the Mac version of Mma.
>>
>> ...
>>______________________________________________________________________
>>Martin Rickli E-mail: Rickli at aut.ee.ethz.ch
>>Automatic Control Laboratory
>>ETH Zurich Physikstr. 3, ETL K12
>>CH-8092 Zurich, Switzerland
>
>We have had problems with SingularValues failing to converge too (at
>MachinePrecision on the Mac). I wish this was fixed.
>
>Stefan