m3core/src/float/IEEE/Real.i3

 Copyright (C) 1991, Digital Equipment Corporation           
 All rights reserved.                                        
 See the file COPYRIGHT for a full description.              
 Last modified on Fri Aug 16 15:06:21 PDT 1996 by heydon     
      modified on Fri Jul  9 16:47:34 PDT 1993 by mhb        
      modified on Wed May  5 08:57:07 PDT 1993 by mcjones    
      modified on Thu Apr 29 16:10:55 PDT 1993 by muller     
      modified on Fri Feb 28 20:50:12 PST 1992 by stolfi     
      modified on Wed Sep 25 00:02:34 1991 by kalsow         


INTERFACE Real;

 Properties of REAL (for ANSI/IEEE Standard 754-1985).


   This package defines some basic properties of the 
   built-in float type REAL.


   Index: REAL; floating-point; generics

  

TYPE T = REAL;

CONST
  Base: INTEGER = 2;
  (* The radix of the floating-point representation for T *)

  Precision: INTEGER = 24;
  (* The number of digits of precision in the given Base for T. *)

  MaxFinite: T = 3.40282347E+38;
  (* The maximum finite value in T.  For non-IEEE implementations,
     this is the same as LAST(T). *)

  MinPos: T = 1.40239846E-45;
  (* The minimum positive value in T. *)

  MinPosNormal: T = 1.17549435E-38;
  (* The minimum positive "normal" value in T; differs from MinPos
     only for implementations with denormalized numbers. *)

CONST
  MaxExpDigits = 2;
  MaxSignifDigits = 9;

 MaxExpDigits is the smallest integer with the property that every
   finite number of type T can be written in base-10 scientific
   notation using an exponent with at most MaxExpDigits.
   MaxSignifDigits is the smallest integer with the property that
   floating-decimal numbers with MaxSignifDigits are more closely
   spaced, all along the number line, than are numbers of type T.
   Typically, 


      MaxExpDigits    = ceiling(log_10(log_10(MaxFinite)))
      MaxSignifDigits = ceiling(log_10(Base^Precision)) + 1.





END Real.