# How to query FLT\_MAX from Ruby code?
**URL:** https://rubytalk.org/t/how-to-query-flt-max-from-ruby-code/3740
**Category:** ruby-talk
**Created:** [21 December 2002 01:17 UTC](https://rubytalk.org/t/how-to-query-flt-max-from-ruby-code/3740 "2002-12-21T01:17:20Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Lyle\_Johnson6](https://rubytalk.org/u/Lyle_Johnson6)
#### Post date: [21 December 2002 01:17 UTC](https://rubytalk.org/t/how-to-query-flt-max-from-ruby-code/3740/1 "2002-12-21T01:17:20Z")
I hope I’m not setting myself up for a Doh! moment…
Is there some way to determine (from Ruby code) the minimum and maximum
limits for Ruby Floats (i.e. along the lines of the C constants FLT\_MIN,
FLT\_MAX, DBL\_MIN and DBL\_MAX from the \ header file)?
---
### Author:  [@HAL\_9000](https://rubytalk.org/u/HAL_9000)
#### Post date: [21 December 2002 03:57 UTC](https://rubytalk.org/t/how-to-query-flt-max-from-ruby-code/3740/2 "2002-12-21T03:57:39Z")
> I hope I’m not setting myself up for a Doh! moment…
>
> Is there some way to determine (from Ruby code) the minimum and maximum
> limits for Ruby Floats (i.e. along the lines of the C constants FLT\_MIN,
> FLT\_MAX, DBL\_MIN and DBL\_MAX from the \ header file)?
Beats me. But if there’s not, maybe there should be.
Time for an RCR? Something like Float::FLT\_MAX etc.?
Hal
> **···**
>
> ----- Original Message -----
> From: “Lyle Johnson” [lyle@users.sourceforge.net](mailto:lyle@users.sourceforge.net)
> Newsgroups: comp.lang.ruby
> To: “ruby-talk ML” [ruby-talk@ruby-lang.org](mailto:ruby-talk@ruby-lang.org)
> Sent: Friday, December 20, 2002 7:17 PM
> Subject: How to query FLT\_MAX from Ruby code?
---
### Author:  [@Bil\_Kleb2](https://rubytalk.org/u/Bil_Kleb2)
#### Post date: [22 December 2002 02:01 UTC](https://rubytalk.org/t/how-to-query-flt-max-from-ruby-code/3740/3 "2002-12-22T02:01:54Z")
Hal E. Fulton wrote:
> > Lyle Johnson wrote:
> >
> > Is there some way to determine (from Ruby code) the minimum and maximum
> > limits for Ruby Floats (i.e. along the lines of the C constants FLT\_MIN,
> > FLT\_MAX, DBL\_MIN and DBL\_MAX from the \ header file)?
>
> Beats me. But if there’s not, maybe there should be.
> Time for an RCR? Something like Float::FLT\_MAX etc.?
Dave sat with me a few years ago and helped me enter an RCR for this. I haven’t
checked it’s status in a year or so. For the time being we apply our own patch
whenever we install ruby. (Included after signature.)
> **···**
>
> –
> Bil Kleb
> NASA Langley Research Center
> Hampton, Virginia, USA
>
> \*\*\* numeric.c 2002/03/12 05:29:13 1.1
> — numeric.c 2002/03/18 12:55:24
>
> * * *
>
> \*\*\* 13,18 \*\*\*\*
> — 13,21 ----
> #include “ruby.h”
> #include \
> #include \
>
> - #ifdef HAVE\_FLOAT\_H
> - #include \
> - #endif
> #if defined( **FreeBSD** ) && **FreeBSD** \< 4
> #include \
> #endif
>
> * * *
>
> \*\*\* 1646,1651 \*\*\*\*
> — 1649,1668 ----
> rb\_define\_singleton\_method(rb\_cFloat, “induced\_from”, rb\_flo\_induced\_from, 1);
> rb\_include\_module(rb\_cFloat, rb\_mPrecision);
>
> - #ifdef HAVE\_FLOAT\_H
> -
>
> ```
> rb_define_const(rb_cFloat, "ROUNDS", INT2FIX(FLT_ROUNDS));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "RADIX", INT2FIX(FLT_RADIX));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "MANT_DIG", INT2FIX(DBL_MANT_DIG));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "DIG", INT2FIX(DBL_DIG));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "MIN_EXP", INT2FIX(DBL_MIN_EXP));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "MAX_EXP", INT2FIX(DBL_MAX_EXP));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "MIN_10_EXP", INT2FIX(DBL_MIN_10_EXP));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "MAX_10_EXP", INT2FIX(DBL_MAX_10_EXP));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "MIN", rb_float_new(DBL_MIN));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "MAX", rb_float_new(DBL_MAX));
>
> ```
>
> -
>
> ```
> rb_define_const(rb_cFloat, "EPSILON", rb_float_new(DBL_EPSILON));
>
> ```
>
> - #endif
> -
>
> ```
> rb_define_method(rb_cFloat, "to_s", flo_to_s, 0);
> rb_define_method(rb_cFloat, "coerce", flo_coerce, 1);
> rb_define_method(rb_cFloat, "-@", flo_uminus, 0);
>
> ```
>
> \*\*\* configure.in 2002/03/18 12:52:21 1.1
> — configure.in 2002/03/18 12:52:26
>
> * * *
>
> \*\*\* 256,262 \*\*\*\*
> AC\_HEADER\_DIRENT
> AC\_HEADER\_STDC
> AC\_HEADER\_SYS\_WAIT
> ! AC\_CHECK\_HEADERS(stdlib.h string.h unistd.h limits.h sys/file.h sys/ioctl.h
> fcntl.h sys/fcntl.h sys/select.h sys/time.h sys/times.h sys/param.h
> syscall.h pwd.h a.out.h utime.h memory.h direct.h sys/resource.h)
>
> — 256,262 ----
> AC\_HEADER\_DIRENT
> AC\_HEADER\_STDC
> AC\_HEADER\_SYS\_WAIT
> ! AC\_CHECK\_HEADERS(stdlib.h string.h unistd.h limits.h float.h sys/file.h sys/ioctl.h
> fcntl.h sys/fcntl.h sys/select.h sys/time.h sys/times.h sys/param.h
> syscall.h pwd.h a.out.h utime.h memory.h direct.h sys/resource.h)
---
### Author:  [@Lyle\_Johnson4](https://rubytalk.org/u/Lyle_Johnson4)
#### Post date: [22 December 2002 14:49 UTC](https://rubytalk.org/t/how-to-query-flt-max-from-ruby-code/3740/4 "2002-12-22T14:49:42Z")
Bil Kleb wrote:
> Dave sat with me a few years ago and helped me enter an RCR for this.
OK, found it here:
```
http://www.rubygarden.org/article.php?sid=103
```
Date is September 21 (not sure of which year).
> I haven’t checked its status in a year or so.
Looks like it’s stuck in RCR limbo, neither accepted nor rejected. I
just added my vote 😉