From: The Written Word Inc <bugs-ruby@...>
Date: 2011-11-15T05:50:05+09:00
Subject: [ruby-core:41042] [ruby-trunk - Bug #5497] Math.log10(10_000) error on HP-UX/PA


Issue #5497 has been updated by The Written Word Inc.


Yui NARUSE wrote:
> The Written Word Inc wrote:
> > $ cat t.c
> > #include <math.h>
> > #include <stdio.h>
> > 
> > int main(void) {
> >   printf("%f\n", log10(10000));
> >   printf("%a\n", log10(10000));
> >   return 0; 
> > }
> > 
> > %a is only supported on HP-UX/IA systems, not HP-UX/PA. We're using the HP-UX C compiler to build Ruby as well.
> 
> OK, can you show a result without %a?
> As B��lka says, this is because it is floating point, but it can be fixed by some options to specify libm as IEEE 754 mode.

$ cat t.c
#include <math.h>
#include <stdio.h>

int main(void) {
  printf("%f\n", log10(10000));
  return 0;
} 

$ cc t.c -lm
$ ./a.out
4.000000
----------------------------------------
Bug #5497: Math.log10(10_000) error on HP-UX/PA
http://redmine.ruby-lang.org/issues/5497

Author: The Written Word Inc
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 1.9.2
ruby -v: UNKNOWN


I've built 1.9.2 from svn revision at 33531 on HP-UX/PA and HP-UX/IA. I'm getting two different results for Math.log10(10_000) depending on IA64 and PA-RISC:
  (ia64)
     p Math.log10(10_000)
     4
  (pa-risc)
     p Math.log10(10_000)
     3.9999999999999996

Any idea where in the code I can look to try and fix this?


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