From: "Tanes Sriviroolchai" <Tanes DOT Sriviroolchai AT Thailand DOT NCR DOT COM>
Newsgroups: comp.os.msdos.djgpp
Subject: Weird results of log( -1.0 ) with libm.a and without libm.a
Date: Thu, 11 Jan 2001 16:49:21 +0700
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com


Hi,
   I'm currently using DJGPP 2.03, gcc 2.95.2. The following short program
gives the different result when using libm.a and when not using libm.a.

#include <stdio.h>
#include <math.h>

main()
{
    double    y;

    y = log( -1.0 );
    printf( "%f\n", y );

    return 0;
}

gcc -o test1.exe test1.c
when running you will get

NaN

This is expected result. However if I compile using
gcc -o test1.exe test1.c -lm
and then running, you will get

-Inf

Is there a report of this error before?

Regards,
Tanes Sriviroolchai