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[Bug-gsl] Strange problem with gsl_eigen_hermv

From: Alexander Klein
Subject: [Bug-gsl] Strange problem with gsl_eigen_hermv
Date: Tue, 28 Dec 2004 14:26:49 +0100


I spent the morning chasing a strange bug:

I've written a wrapper class in Smalltalk, so I can use the GSL from Cincom VisualWorks.

Trying to compute the eigenvalues and -vectors of the 4*4 Hilbert matrix from the GSL-manual, the Smalltalk version always came up with a lot of NaNs instead of the correct result.

Checking with gdb, I found that the data passed to gsl_eigen_hermv was definitely correct, but strangely enough, a C program that passed exactly the same data ran without problems.

After some further experimentation, it turned out that the problem went away after recompiling GSL with

setenv CFLAGS -O0

I use gcc 3.4.0 on a Pentium-IV running Suse Linux 9.0
The GSL-version is 1.5

Unfortunately, a sample program in Smalltalk is not really what you would call a 'minimal example', so I won't send the whole class definition here, but if there's any other information I can provide to track the bug, I'll be glad to do so.

Thank you anyway for providing the GSL. It saves so much work!

Best regards,

        Alex Klein

Alexander Klein, Diplom-Mathematiker
Lehrstuhl für Numerische Mathematik
Heinrich-Buff-Ring 44
35392 Giessen

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