From: Yui NARUSE <naruse@...>
Date: 2011-10-29T14:29:05+09:00
Subject: [ruby-core:40501] [ruby-trunk - Bug #5497] Math.log10(10_000) error on HP-UX/PA


Issue #5497 has been updated by Yui NARUSE.


The Written Word Inc wrote:
>   (ia64)
>      p Math.log10(10_000)
>      4

Show the result of `p 4.0`.

>   (pa-risc)
>      p Math.log10(10_000)
>      3.9999999999999996

Build and run following C code:

% cat f.c
#include <math.h>
#include <stdio.h>

int main(void) {
  printf("%a\n", log10(10000));
  return 0;
}
%  gcc -lm f.c && ./a.out
0x1p+2 (or something)
----------------------------------------
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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