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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: precise floats
Date: 1998/08/06
Message-ID: <dewar.902417129@merv>#1/1
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Date: 1998-08-06T00:00:00+00:00
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C Green said
<<
  In article <6q7vtb$jk$1@heliodor.xara.net>,
  Bob Fletcher <bob@radge.nospam.globalnet.co.uk> wrote:
    What is the best way to define a float type that has greater precision,
    (like a lot greater), than the default one? Is there a simple way to do
    this?
  
      type my_very_precise_type is digits <N>;
  
  where <N> is the number of digits of precision you need.  Be aware, however,
  that few compilers support float types of precision greater than 15 digits.
>>

Surely better advice is

     type my_very_precise_type is System.Max_Digits;

<<
  If you have an application that depends on floating-point calculations of
  very high precision, be especially careful in numerical analysis, design,
  and testing.  Don't accept vendor's claims that their numerical libraries
  perform correctly; test them in computations that are required in your
  application.
>>

or insist on Annex G validation. For almost all purposes, the ACVC
validation tests for accuracy of elementary functions should prove
adequate.