On November 19, 2001 02:36 pm, Jeff Whitaker wrote:

This is definitely a hardware/compiler dependant feature. I get the "right" answer on Solaris (with the forte compiler) but the same "wrong" answer as Alessandro on MacOS X/gcc. I've tried fiddling with compiler options on my OS X box, to no avail.

But seemingly it is even stranger than this. Here are my results from Debian unstable using Lapack 3.0 on an Athlon system: Python 2.1.1 (#1, Nov 11 2001, 18:19:24) [GCC 2.95.4 20011006 (Debian prerelease)] on linux2 Type "copyright", "credits" or "license" for more information.

...

...

from LinearAlgebra import * a=array([[1,0],[0,1]]) b=array([[0,1],[-1,0]]) M=a+b*complex(0,1.0) Heigenvalues(M) array([ 0., 2.])

Scott

On Sun, 18 Nov 2001, Travis Oliphant wrote:

...

On Sunday 18 November 2001 09:40 am, Alessandro Mirone wrote:

...

Is it a problem of lapack3.0 of of LinearAlgebra.py? ..................... ==> (Eigenvalues should be (0,2))

...

...

...

a=array([[1,0],[0,1]]) b=array([[0,1],[-1,0]]) M=a+b*complex(0,1.0) Heigenvalues(M)

I suspect it is your lapack. On an Athlon running Mandrake Linux with the lapack-3.0-9 package, I get.

...

...

...

a=array([[1,0],[0,1]]) b=array([[0,1],[-1,0]]) M=a+b*complex(0,1.0) Heigenvalues(M)

array([ 0., 2.])

This is definitely a hardware/compiler dependant feature. I get the "right" answer on Solaris (with the forte compiler) but the same "wrong" answer as Alessandro on MacOS X/gcc. I've tried fiddling with compiler options on my OS X box, to no avail.

-Jeff

-- Jeffrey S. Whitaker Phone : (303)497-6313 Meteorologist FAX : (303)497-6449 NOAA/OAR/CDC R/CDC1 Email : jsw@cdc.noaa.gov 325 Broadway Web : www.cdc.noaa.gov/~jsw Boulder, CO, USA 80303-3328 Office : Skaggs Research Cntr 1D-124

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-- Scott M. Ransom Address: McGill Univ. Physics Dept. Phone: (514) 398-6492 3600 University St., Rm 338 email: ransom@physics.mcgill.ca Montreal, QC Canada H3A 2T8 GPG Fingerprint: 06A9 9553 78BE 16DB 407B FFCA 9BFA B6FF FFD3 2989

On November 19, 2001 02:36 pm, Jeff Whitaker wrote:

This is definitely a hardware/compiler dependant feature. I get the "right" answer on Solaris (with the forte compiler) but the same "wrong" answer as Alessandro on MacOS X/gcc. I've tried fiddling with compiler options on my OS X box, to no avail.

But seemingly it is even stranger than this. Here are my results from Debian unstable using Lapack 3.0 on an Athlon system: Python 2.1.1 (#1, Nov 11 2001, 18:19:24) [GCC 2.95.4 20011006 (Debian prerelease)] on linux2 Type "copyright", "credits" or "license" for more information.

...

...

from LinearAlgebra import * a=array([[1,0],[0,1]]) b=array([[0,1],[-1,0]]) M=a+b*complex(0,1.0) Heigenvalues(M) array([ 0., 2.])

Scott

On Sun, 18 Nov 2001, Travis Oliphant wrote:

...

On Sunday 18 November 2001 09:40 am, Alessandro Mirone wrote:

...

Is it a problem of lapack3.0 of of LinearAlgebra.py? ..................... ==> (Eigenvalues should be (0,2))

...

...

...

a=array([[1,0],[0,1]]) b=array([[0,1],[-1,0]]) M=a+b*complex(0,1.0) Heigenvalues(M)

I suspect it is your lapack. On an Athlon running Mandrake Linux with the lapack-3.0-9 package, I get.

...

...

...

a=array([[1,0],[0,1]]) b=array([[0,1],[-1,0]]) M=a+b*complex(0,1.0) Heigenvalues(M)

array([ 0., 2.])

This is definitely a hardware/compiler dependant feature. I get the "right" answer on Solaris (with the forte compiler) but the same "wrong" answer as Alessandro on MacOS X/gcc. I've tried fiddling with compiler options on my OS X box, to no avail.

-Jeff

-- Jeffrey S. Whitaker Phone : (303)497-6313 Meteorologist FAX : (303)497-6449 NOAA/OAR/CDC R/CDC1 Email : jsw@cdc.noaa.gov 325 Broadway Web : www.cdc.noaa.gov/~jsw Boulder, CO, USA 80303-3328 Office : Skaggs Research Cntr 1D-124

_______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion

-- Scott M. Ransom Address: McGill Univ. Physics Dept. Phone: (514) 398-6492 3600 University St., Rm 338 email: ransom@physics.mcgill.ca Montreal, QC Canada H3A 2T8 GPG Fingerprint: 06A9 9553 78BE 16DB 407B FFCA 9BFA B6FF FFD3 2989