[Numpy-discussion] QR algorithms in Python

Nils Wagner nwagner at mecha.uni-stuttgart.de
Tue Aug 13 04:53:02 CDT 2002


James G Analytis schrieb:
> 
> Dear Pearu,
> SciPy's linalg modules are just what I need. However, I get the following
> problem on importing SciPy:
> 
ATLAS is also required.

http://math-atlas.sourceforge.net/

Nils

> [analytis at toomey analytis]$ python2
> Python 2.2 (#1, Apr 12 2002, 15:29:57)
> [GCC 2.96 20000731 (Red Hat Linux 7.2 2.96-109)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import scipy
> exceptions.ImportError:
> /usr/lib/python2.2/site-packages/scipy/linalg/flapack.so     : undefined
> symbol: sgesdd_
> exceptions.ImportError:
> /usr/lib/python2.2/site-packages/scipy/linalg/_flinalg.s     o: undefined
> symbol: dlaswp_
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
>   File "/tmp/SciPyTest/linux2/lib/python2.2/site-packages/scipy/__init__.py",
> li     ne 42, in ?
>   File "/usr/lib/python2.2/site-packages/scipy/special/__init__.py", line 328,
> i     n ?
>     import orthogonal
>   File "/usr/lib/python2.2/site-packages/scipy/special/orthogonal.py", line
> 59,      in ?
>     from scipy.linalg import eig
>   File
> "/tmp/SciPyTest/linux2/lib/python2.2/site-packages/scipy/linalg/__init__.
> py", line 40, in ?
>   File
> "/tmp/SciPyTest/linux2/lib/python2.2/site-packages/scipy/linalg/basic.py"
> , line 17, in ?
> ImportError: /usr/lib/python2.2/site-packages/scipy/linalg/calc_lwork.so:
> undefi     ned symbol: ieeeck_
> >>>
> 
> I am running standard Red Hat 7.3 with a smp kernel, on a dual-processor PIII.
> Is there anything I should watch out for (compiler issues perhaps)?
> I appreciate the help!
> Cheers,
> James
> 
> On Monday 12 Aug 2002 9:04 am, Pearu Peterson wrote:
> > On Mon, 12 Aug 2002, James G Analytis wrote:
> > > Hi,
> > > I'm looking for a QR algorithm that can decompose complex matrices. The
> > > LinearAlgebra package from Numeric doesn't seem to have it. SciPy's
> > > linalg package is still on the way, so I can't use that either.
> >
> > Try SciPy's linalg package again (from CVS), the QR functions is working
> >
> > now:
> > >>> from scipy import linalg
> > >>> from Numeric import dot
> > >>> q,r=linalg.qr([[1,2],[3j,4]])
> > >>> print q
> >
> > [[-0.31622777+0.j         -0.78935222-0.52623481j]
> >  [ 0.        -0.9486833j  -0.1754116 +0.26311741j]]
> >
> > >>> print r
> >
> > [[-3.16227766+0.j         -0.63245553+3.79473319j]
> >  [ 0.        +0.j         -2.28035085+0.j        ]]
> >
> > >>> print dot(q,r)
> >
> > [[ 1. +0.00000000e+00j  2. -8.71264866e-16j]
> >  [ 0. +3.00000000e+00j  4. +3.09051829e-16j]]
> >
> > Regards,
> >       Pearu
> 
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