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Bug in gsl_integration_qawc and correction
- From: Axel Hutt <hutt at wias-berlin dot de>
- To: gsl-discuss at sources dot redhat dot com
- Date: Wed, 08 Jan 2003 18:20:41 +0100
- Subject: Bug in gsl_integration_qawc and correction
- Organization: Weiertrass-Institute Berlin
Dear all,
there is a bug in the quadrature routine for Cauchy principal
values in gsl_integration_qawc.
The problem is, that for a special relation of integration interval
(a,b) and singularity, the bisection routine in
$(GSL-ROOT-DIR)/integration/qawc.c might lead to integration borders
a1=c or b1=c, which yields NaN from qc25c(..) for the integral.
This is easily resolved by changing the check in which subinterval
c lies (line 133) from
if (c > a1 && c < b1)
to
if (c >= a1 && c <= b1)
(or equivalently for a2 and b2 in line 138), just add equation signs
in qawc.c in line 133.
Unfortunately, I do not know how to handle patch files, sorry for
this.
Axel