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[bug-gsl] Re: Bug in sys/ldfrexp.c (2007-10-29)

From: Brian Gough <bjg@network-theory.co.uk>
Subject: Re: Bug in sys/ldfrexp.c
Date: Mon, 29 Oct 2007 21:37:43 +0000
To: "Chris Mihelich" <umbricola@.........>
Cc: bug-gsl@gnu.org

At Sat, 27 Oct 2007 19:47:12 -0400,
Chris Mihelich wrote:
> I wish to report and correct the following bugs in sys/ldfrexp.c:
>
> (1) gsl_ldexp computes a power of 2 (p2) that may overflow or
> underflow even though the correct answer is representable;
> consequently the return value x * p2 may be spuriously zero or
> infinity.
>
> (2) gsl_frexp can hang (this is what bit me in the rear at work
> yesterday) if its call to gsl_ldexp spuriously returns zero or
> infinity as in (1). The first while loop divides infinity by 2.0 over
> and over and wonders why it doesn't get any smaller; the second while
> loop has an analogous problem with zero.

Thanks for the bug report and code. I will fix those problems for
the next release.

--
best regards,

Brian Gough
(GSL Maintainer)

Network Theory Ltd,
Commercial support for GSL --- http://www.network-theory.com/gsl/