From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,5291fa0ea59b8b29
X-Google-Attributes: gid103376,public
From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Random Number Generation
Date: 1996/10/02
Message-ID: <EACHUS.96Oct2162609@spectre.mitre.org>#1/1
X-Deja-AN: 186762009
references: <5266q1$a0t@netty.york.ac.uk>
 <Dy7CMw.A7v.0.-s@inmet.camb.inmet.com>
organization: The Mitre Corp., Bedford, MA.
newsgroups: comp.lang.ada
Date: 1996-10-02T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <52ten0$ish@netty.york.ac.uk> njt@minster.york.ac.uk (Nigel J. Tracey) writes:

  > Thanks for all the replies on this issue. I now have the problem
  > sorted for discrete random values. However nobody has suggested
  > a solution for generating large random reals. I really need
  > to be able to generate random values in the range of
  > Float'Safe_First..Float'Safe_Last. Or perhaps a variable
  > sub-range of these. Any idea...

  With what distribution?  If you are using this for testing
arithmetic units, I suggest unchecked converting a string of random
bits of the right length.  This will be a distribution which covers
all representable numbers equally. (To save Robert Dewar the
trouble...Certain bit patterns do not correspond to legal floating
point values.  This a legitimate use for 'VALID).  However if you want
a numerically uniform distribution:

   2.0 * Float'Safe_Last * (Ada.Numerics.Float_Random.Random(Gen) - 0.5);

   Actually you may want to add more bits to the typical floating
point generator value.


--

					Robert I. Eachus

with Standard_Disclaimer;
use  Standard_Disclaimer;
function Message (Text: in Clever_Ideas) return Better_Ideas is...