![]() Jacques-Louis Lions, Lennart Lebeck, Jean-Luc Fauquembergue, Gilles.Rules in the Appendix C of Writing Efficient Programs. For ease of presentation, he codified his methods as a set of terse Pragmatic treatment of program efficiency, independent of language and host Writing Efficient Programs, in which he provides a unified, Jon Bentley, author of Programming Pearls, published Performance Computing) in C, or why Fortran is often referred to as the Robison, C/C++ Users Journal,Īlias Analysis, Optimization that makes C++ faster than C, Or undefinition of an actual argument of the function, thatĪrgument or any associated entities shall not appear elsewhere in If a function reference causes definition The evaluation of a function reference shall neitherĪffect nor be affected by the evaluation of any other entity Evaluation rules related to "Function" are exposed in section.Restrictions on dummy arguments are discussed in Fortranĩ0/95 Explained, M.That is, some people like to enter 0.1 and not get 0.09999997 back.įor this, the maximum decimal digits you should use for the IEEE and To decimal and get the same answer, the required relation between the Similarly, if you want to translate from decimal to binary and back For Intel's version of double extended, you have B=64, For IEEE double, B is 53 and you wantĭ=17 (or more). Precision, the number of bits is 24 (counting the hidden normalization) To binary again is an identity operation. ![]() If that's the case, then translating the binary to decimal and back The number of binary bits B should be related as follows: 8,īasically, the condition is that the number of decimal digits D, and Matula, A Formalization of Floating-Point Numeric BaseĬonversion, IEEE Transactions on Computers, vol. Proceedings of International Conference on Supercomputing (ICS'00), Mayĭ. Of Supercomputing, Vol.18, Issue 3, March 2001, pp. In parallel applications, Yun He and Chris H.Q. Higham, SIAM, 2002: the reference on the subjectĪccurate arithmetics to improve numerical reproducibility and stability Stability of Numerical Algorithms, Second edition, Nicholas J. IEEE 754 Implementations by Doug Priest (included in theĬomputing with IEEE Floating Point Arithmetic, Michael L. Version including Doug Priest's supplement. Version (from Sun's Numerical Computation Guide Goldberg, David, What Every Computer Scientist Should KnowĪbout Floating-Point arithmetic, ACM Computing Surveys, Vol.One can refer to uninit.c in the source of libf2c. The code included is now obsolete.Ĭopy, it may still provide some useful information. Posted on Usenet in July 1999 a clear explanation of the problem Munro of LLNL, contains a comprehensive inventory of theseĪPIs in play/unix/. Several packages contain some relevant code:ĭavid H. Here are the main ones: Linux (and glibc based systems) feenableexcept ( 1, 2) Microsoft Windows _controlfp or _control87 ( 1) x86/x86_64 based systems refer to ( 1) This can be usually overwritten by using a compiler flag ( C/C++, Fortran) or by callingĪ system API in order to modify the exception mask. Up and consequently do not get delivered synchronously to the program. Most implementations default to the "non stopĪrithmetic" behaviour where arithmetic exceptions are masked at start Language Independent Arithmetic ( ISO/IEC 10967) defines some.The ANSI/IEEE Std 854-1987 standard allows both binary and decimalīases for floating-point values, and it doesn't specify howįloating-point numbers are encoded (i.e. Standard: IEC 559:1989 and has also been published as ACM SIGPLAN The 754 standard, which is document ANSI/IEEE Std 754-1985, also an IEC There are two different IEEE standards for floating-pointĪrithmetic. Theoretical background Floating point arithmetic IEEE Standards for Floating-Point Arithmetic disallow implicit declaration ( Fortran).stack oriented/static allocation ( Fortran).take advantage of aliasing rules ( C/C++).abort on deferencing null pointer ( C/C++) ( Fortran).put literal strings in read-only memory ( C/C++) ( Fortran).run-time detection of uninitialized variable ( C/C++) ( Fortran).standard conformance ( C/C++) ( Fortran).floating point trapping ( C/C++) ( Fortran).Exchange Fortran unformatted data between. ![]() Sounds familiar? But with which option? This page tries to answer that Steve Macguire, Writing solid code, 1993 Unless you have an excellent reason not to. Warning?" Instead ask, "Why shouldn't I enable it?" Turn on every warning Kernighan, Rob Pike, The practice ofĮnable every optional warning view the warnings as a risk-free, Has become clear that you have the wrong picture of how the code Use some of the commercial tools that check for memory leaks, array bounds Explaining your code to someone else (evenĪ teddy bear) is wonderfully effective. Compiler and tools tricks Compiler and tools tricks
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