Evaluation of Intrinsic Procedures
To: J3
From: Craig Dedo
Date: May 31, 2000
Subject: Interpretation 12 - Evaluation of Intrinsic Procedures
NUMBER: 000012
TITLE: Evaluation of Intrinsic Procedures
KEYWORDS: Algorithm, Mathematical, Computational
DEFECT TYPE: Interpretation
STATUS: J3 Consideration in Progress
QUESTION:
1. When the standard specifies an algorithm for computing a mathematical procedure, must a processor use the
specified algorithm?
Example: ANINT is defined as INT (A + 0.5). On some processors ANINT (16 000 001.0) evaluates to
16 000 002.0 using this algorithm.
2. May a processor return a mathematically equivalent result in the evaluation of a numeric intrinsic procedure?
Example: If ANINT (16 000 001.0) can be computed as the more expected 16 000 001.0, may a processor do so?
ANSWER:
1. No, a processor is not required to use the algorithm from the standard.
2. Yes, a processor may return the mathematically equivalent result in the evaluation of any numeric intrinsic
procedure.
DISCUSSION:
The use of an algorithm in the definitions for intrinsic procedures is intended to describe the end result. It is not
intended to require that a processor use a particular method of achieving that result. Thus, an algorithm specifies
the mathematical results, not the computational results, of the evaluation of intrinsic procedures.
This standard does not require a processor to use a particular accuracy or precision. Section 1.4, "Exclusions",
states in part:
"This standard does not specify: . . .
(6) The physical properties of the representation of quantities and the method of rounding,
approximating, or computing numeric values on a particular processor." [1:26, 1:37-38]
EDITS: None.
SUBMITTED BY: Keith H. Bierman
HISTORY: 95-247r1 m134 Submitted as F90 interp 000202 with proposed response, approved 9-4,
subsumes F90 interp 000200.
95-256 m134 Ballot failed, 10-6
95-260 m135 Proposed response, no action
96-023 m136 Proposed response, no action
96-054 m137 Proposed response, no action
96-117 m138 Proposed response, no action
97-259r1 m143 Re-submitted as F95 interp 000012 with proposed response
00-214 m153 Proposed response
[End of J3 / 00-214]