Copyright (C) 1994, Digital Equipment Corp. INTERFACEProperties of EXTENDED (for the VAX).Extended ;
This package defines some basic properties of the built-in float type EXTENDED, for the VAX architecture.
Index: EXTENDED; floating-point; generics
TYPE T = EXTENDED; CONST Base: INTEGER = 2; (* The radix of the floating-point representation for T *) Precision: INTEGER = 56; (* The number of digits of precision in the given Base for T. *) MaxFinite: T = 1.70141183460469230X+38; (* The maximum finite value in T. For non-IEEE implementations, this is the same as LAST(T). *) MinPos: T = 2.93873587705571880X-39; (* The minimum positive value in T. *) MinPosNormal: T = MinPos; (* The minimum positive "normal" value in T; differs from MinPos only for implementations with denormalized numbers. *) CONST MaxExpDigits = 2; MaxSignifDigits = 18;
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 Extended.