[Numpy-discussion] QR algorithms in Python

James G Analytis james.analytis at physics.ox.ac.uk
Tue Aug 13 04:36:03 CDT 2002


Dear Pearu,
SciPy's linalg modules are just what I need. However, I get the following 
problem on importing SciPy:

[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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