[SciPy-User] lstsq error under Windows?

[josef.pktd at gmail.com]

On Tue, May 4, 2010 at 4:27 PM,  <bruce.labitt at autoliv.com> wrote:
> scipy-user-bounces at scipy.org wrote on 05/04/2010 03:48:55 PM:
>
>> I have found an issue with scipy.linalg.lstsq, I think.  The following
>> code works in Ubuntu 10.04 x86-64, but not in WinXP-32.  I think it
> should
>> work in WinXP.  Here is a minimum example:
>>
>> """==== program testlstsq.py ======================"""
>> from scipy.linalg import eig, lstsq
>> from numpy import angle, zeros, pi, arcsin
>>
>> A = zeros((4,1), dtype='complex')
>> B = zeros((4,1), dtype='complex')
>>
>> A[0,0] = -0.535412460549-2.65798938848e-17j
>> A[1,0] = -0.369432866546-0.131765700574j
>> A[2,0] = -0.222906796932-0.263237285725j
>> A[3,0] = -0.069087096386-0.38609560454j
>>
>> B[0,0] = -0.369432866546-0.131765700574j
>> B[1,0] = -0.222906796932-0.263237285725j
>> B[2,0] = -0.069087096386-0.38609560454j
>> B[3,0] =  0.0882283631514-0.528093039953j
>>
>> try:
>>     print 'Got here'
>>     phi = lstsq(A,B)
>>     print 'Finished lstsq'
>> except:
>>     print 'Exception Occurred'
>> else:
>>     for a in range(len(phi)):
>>         print 'phi[',a,']=',phi[a]
>>
>>     w = -angle( eig(phi[0])[0][:] )
>>     d = 0.5
>>     aa = arcsin( w / (2.0*pi) )*180./pi     # in degrees
>>     print 'aa unsorted =', aa
>> """ ==== end of testlstsq.py =========================="""
>>
>> If this is run under ipython, or python on Ubuntu, the answer is:
>>
>> In [3]: run testlstsq.py
>> Got here
>> Finished lstsq
>> phi[ 0 ]= [[ 0.88271111+0.38811028j]]
>> phi[ 1 ]= [-0.04649206-0.01274722j]
>> phi[ 2 ]= 1
>> phi[ 3 ]= [ 0.84459073]
>> aoa unsorted = [-3.780145]
>>
>> If testlstsq.py is run under WinXP-32 one gets the following result:
>> > python testlstsq.py
>> Got here
>>  ** On entry to ZGELSS parameter number 12 had an illegal value
>>
>> I think that ZGELSS is in LAPACK.  After that, I am in over my head. Can
>
>> someone help with this?
>>
>> Under Windows I am running:
>> WinXP-x86-32
>> Python(x,y)2.6.2.0 --> Python 2.6.2
>> numpy 1.3.0
>> scipy 0.7.1
>> ipython 0.10
>>
>> For Linux, Ubuntu 10.04 x86-64
>> Python 2.6.5
>> numpy 1.30
>> scipy 0.7.0-2
>> ipython 0.10-1
>>
>> Thanks for any and all help!
>> -Bruce
>>
>>
>
> Per Josef's observation that scipy.linalg.lstsq and numpy.lstsq behaved
> the same for him, I tried changing my code to
>
> - from scipy.linalg import eig, lstsq
> + from scipy.linalg import eig
> + from numpy.linalg import lstsq
>
> and reran the code and got -
>>pythonw -u "testlstsq.py"
> Got here
> Finished lstsq
> phi[ 0 ]= [[ 0.88271111+0.38811028j]]
> phi[ 1 ]= [-0.04649206-0.01274722j]
> phi[ 2 ]= 1
> phi[ 3 ]= [ 0.84459073]
> aoa unsorted = [-3.780145]
>>Exit code: 0
>
> So scipy.linalg.lstsq version 0.7.1 under WinXP-32 faults using the CME
> and
> numpy.linalg.lstsq version 1.3.0 does not.
>
> It looks like I have an answer for now, and scipy dev's might have a
> mini-testbench to test against.

It could be that this is a problem with the transition to python 2.6,
that might have gone away in the meantime. I never had problems with
python 2.5 and scipy.linalg

Josef

>
> Thanks for the help!
> -Bruce
>
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