From: Bil Kleb <W.L.Kleb@...>
Date: 2002-12-22T11:01:54+09:00
Subject: Re: How to query FLT_MAX from Ruby code?

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 <limits.h> 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 <math.h>
   #include <stdio.h>
+ #ifdef HAVE_FLOAT_H
+ #include <float.h>
+ #endif
   #if defined(__FreeBSD__) && __FreeBSD__ < 4
   #include <floatingpoint.h>
   #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)