J3/05-206 Date: 10 Jun 2005 To: J3 From: Fred Tydeman Subject: Accuracy of conversion of real literal constants NUMBER: F03/0067 TITLE: Accuracy of conversion of real literal constants KEYWORDS: conversion, accuracy DEFECT TYPE: Interpretation STATUS: For consideration QUESTION: The following is independent of IEEE-754. Fortran 2003 10.6.1.2.6 covers conversions between "decimal values" and "internal values" and has some strong requirements. Are there equivalent requirements on accuracy for conversions of real literal constants? Sections 4.1.2 and 4.4.2 seems like the places to find them (if they exist). What rounding mode is used for conversions of real literal constants? Is the same rounding mode used for all such conversions? The following four questions are about positive values, but the same would apply to negative values. Must all "decimal values" in the range smallest non-zero finite internal value (which could be a denormal) to largest finite internal value, e.g. 0.1, be converted? Must all "decimal values" in the range zero to smallest non-zero finite internal value, e.g. 1.0e-999999999, be converted? Must all "decimal values" larger than the largest finite internal value, e.g. 9.9e+99999999999, be converted if infinity is an internal value? What does nearest rounding mean for these cases? What requirements exist for "decimal values" larger than the largest finite internal value if infinity is not an internal value? ANSWER: DISCUSSION: EDITS: SUBMITTED BY: Fred Tydeman HISTORY: J3/05-206 m173 Submitted ---