From: nobu@...
Date: 2017-07-11T05:11:25+00:00
Subject: [ruby-core:81997] [Ruby trunk Bug#5497] Math.log10(10_000) error on	HP-UX/PA

Issue #5497 has been updated by nobu (Nobuyoshi Nakada).


Please try more precision.
The default precision doesn't seem enough.

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

int main(void) {
  printf("%.19f\n", log10(10000));
  return 0;
}
```

----------------------------------------
Bug #5497: Math.log10(10_000) error on HP-UX/PA
https://bugs.ruby-lang.org/issues/5497#change-65729

* Author: twwlogin (The Written Word Inc)
* Status: Feedback
* Priority: Normal
* Assignee: takano32 (Mitsuhiro TAKANO)
* Target version: next minor
* ruby -v: UNKNOWN
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: 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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