m3core/src/float/IEEE/LongReal.i3

 Copyright (C) 1991, Digital Equipment Corporation           
 All rights reserved.                                        
 See the file COPYRIGHT for a full description.              
 Last modified on Fri Aug 16 15:09:23 PDT 1996 by heydon     
      modified on Wed May  5 08:13:33 PDT 1993 by mcjones    
      modified on Thu Apr 29 16:10:49 PDT 1993 by muller     
      modified on Fri Feb 28 20:35:22 PST 1992 by stolfi     
      modified on Wed Sep 25 00:03:30 1991 by kalsow         


INTERFACE LongReal;

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


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


   Index: LONGREAL; floating-point; generics



TYPE T = LONGREAL;

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

  Precision: INTEGER = 53;
  (* The number of digits of precision in the given Base for T. *)

  MaxFinite: T = 1.7976931348623157D+308;
  (* The maximum finite value in T.  For non-IEEE implementations,
     this is the same as LAST(T). *)

  MinPos: T = 4.9406564584124654D-324;
  (* The minimum positive value in T. *)

  MinPosNormal: T = 2.2250738585072014D-308;
  (* The minimum positive "normal" value in T; differs from MinPos
     only for implementations with denormalized numbers. *)

CONST
  MaxExpDigits = 3;
  MaxSignifDigits = 17;

 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 LongReal.