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From: sbc@informatics.wustl.edu (Steve Cousins)
Newsgroups: comp.soft-sys.andrew
Subject: wierd behavior
Message-ID: <9105161920.AA02290@informatics.WUstl.EDU>
Date: 16 May 91 19:20:33 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 61


I'm having a lot of trouble tracking down a bug, which only comes up when
my code is linked in to ATK.  The following program works fine:


#include <math.h>

main()
{
  int bigN = 4181;
  int ndocs = 4;
  double log_val;

	log_val = log((double)bigN/(double)ndocs);
	printf("log(%f/%f) = %f or %f\n",
	       (double)bigN, (double)ndocs, log_val,
	       log((double)bigN/(double)ndocs));
}

when compiled with "cc foo.c -lm" or with "gcc foo.c -lm" on either a
Sparcstation 330 with SunOS 4.1 or a Sparcstation 470 with SunOS 4.1.1.
(I've tried all the experiments I'll describe on both of these platforms).

When I include this code segment in an ATK program, things act very strangly.
The correct answer is:
log(4181.000000/4.000000) = 6.952011 or 6.952011

From the ATK version I get
log(4181.000000/4.000000) = 1072715008.000000 or 1.020752

and if (in the ATK version) I move that calculation of the log from the
last arg to printf to the first argument after the control string, I get:
log(1.020752/0.000000) = 0.000000 or -0.000000

This tells me that maybe log is returning something of a different length
than the C compiler thinks.  Anyway, it's very frustrating because I got
the code to work standalone, but can't seem to embed it in the ATK application.

My Imakefile has the line:
DynamicMultiObject(searchv.do, searchv.o, /usr/desert/sybase/lib/libsybdb.a, -lm)

which generates the commands:

rm -f searchv.o
cc -c -I. -I/usr/desert/sybase/include/ -g -I/usr/andrew/include/atk -I/usr/andrew/include -I//usr/include/X11   searchv.c
/usr/desert/sybase/include//sybfront.h: 164: MAX redefined
/usr/desert/sybase/include//sybfront.h: 165: MIN redefined
/usr/andrew/bin/makedo -g -d /usr/andrew/lib -b /usr/andrew/bin -o searchv.do  searchv.o  /usr/desert/sybase/lib/libsybdb.a  -lm
doindex: indexing searchv.do ...OK
doindex: Writing index file...Done

Can anyone see anything I'm doing that's obviously wrong?  What
version of "log" is getting called?  Any help is appreciated, as I'm
at a loss as to how to proceed at this point.

Thanks

Steve Cousins
Medical Informatics Laboratory
Washington University
St. Louis, MO