[Maxima] Can't find eigenvalues

Javed Alam jalam1001 at gmail.com
Thu Dec 11 00:11:59 CST 2008

```Yes it looks like it. I had problem with eig(a) function but
eigens_by_jacobi worked for the matrix I was using as shown in that
example..

On Thu, Dec 11, 2008 at 1:07 AM, Noparit Jinuntuya <fscinpr at yahoo.com>wrote:

> Many thanks for your advice. But eigens_by_jacobi works only with a real
> symmetric matrix. Isn't it?
>
> Anyway, I try
>
> (%i2) b:matrix([0,-1/4,0,0],[1/4,0,0,0],[0,0,0,-1/4],[0,0,1/4,0])\$
> (%i3) eigens_by_jacobi(b);
>
> and Maxima gives
>
> The first argument to eigens_by_jacobi must be a real symmetric matrix
>  -- an error.  To debug this try debugmode(true);
>
> Noparit
>
> --- On *Wed, 12/10/08, Javed Alam <jalam1001 at gmail.com>* wrote:
>
> From: Javed Alam <jalam1001 at gmail.com>
> Subject: Re: [Maxima] Can't find eigenvalues
> To: fscinpr at yahoo.com, maxima at math.utexas.edu
> Date: Wednesday, December 10, 2008, 9:50 PM
>
>
> You can try the following function of Maxima since your matrix is all
> numeric
>
>
> m : matrix([14,32,50],[32,77,122],[50,122,194]);
>
> e : eigens_by_jacobi(m);
>
>
> More details at
> http://www.eng.ysu.edu/~jalam/engr6924s07/sessions/session15/session15.htm<http://www.eng.ysu.edu/%7Ejalam/engr6924s07/sessions/session15/session15.htm>
>
>
> Javed
>
> http://www.eng.ysu.edu/~jalam/engr6924s07/<http://www.eng.ysu.edu/%7Ejalam/engr6924s07/sessions/session15/session15.htm>
>
>
>
> On Wed, Dec 10, 2008 at 11:52 PM, Noparit Jinuntuya <fscinpr at yahoo.com>wrote:
>
>> Many thanks.
>>
>> For this bug, it may be interesting to note that, by little modification
>>
>> (%i1) b:matrix([0,-1/4,0,0],[1/4,0,0,0],[0,0,0,-1/4],[0,0,1/4,0])\$
>> (%i2) eigenvalues(4*b);
>>
>> Maxima give the correct answer,
>>
>> (%o2) [[-%i,%i],[2,2]]
>>
>> Noparit
>>
>> --- On *Wed, 12/10/08, Barton Willis <willisb at unk.edu>* wrote:
>>
>> From: Barton Willis <willisb at unk.edu>
>> Subject: Re: [Maxima] Can't find eigenvalues
>> To: fscinpr at yahoo.com
>> Cc: maxima at math.utexas.edu
>> Date: Wednesday, December 10, 2008, 3:25 AM
>>
>>
>> You found a bug, I'm sorry to say. I'm pretty sure that the bug is due
>> to a faulty computation of the multiplicities of the roots of the
>> characteristic polynomial:
>>
>>
>>  (%i26)
>>  solve(g33664^2*(g33664^2+1/16)+(g33664^2+1/16)/16,g33664);
>>  (%o26) [g33664=-%i/4,g33664=%i/4]
>>
>>  (%i27) multiplicities;
>>  (%o27) [1,1]
>>
>> I think (%o27) should be [2,2]. I can't think of a workaround; I'll
>>
>> file a bug report.
>>
>> Barton
>>
>> -----maxima-bounces at math.utexas.edu wrote:
>>  -----
>>
>>
>> >I'm trying to find the eigenvalues of a simple matrix
>> >
>> >b:matrix([0,-1/4,0,0],[1/4,0,0,0],[0,0,0,-1/4],[0,0,1/4,0]);
>> >
>> >by
>> >
>> >eigenvalues(b);
>> >
>> >But Maxima give me
>>
>> >
>> >part fell off end.
>> >#0:
>> >eigenvalues(mat=matrix([0,-1/4,0,0],[1/4,0,0,0],[0,0,0,-1/4],[0,0,1/4,0]))
>> >(eigen.mac line 94)
>> >-- an error.  To debug this try debugmode(true);
>> >
>> >What wrong with this? Can anyone help?
>>
>> >
>> >Noparit Jinuntuya
>> >Department of Physics, Kasetsart University
>> >Thailand.
>> >
>> >
>> >
>> >
>> >
>> >_______________________________________________
>> >Maxima mailing list
>>
>> >Maxima at math.utexas.edu
>> >http://www.math.utexas.edu/mailman/listinfo/maxima
>>
>>
>>
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>>
>
>
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