Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!mintaka!spdcc!esegue!compilers-sender From: robertsj@admin.ogi.edu (John Roberts) Newsgroups: comp.compilers Subject: IEEE 754 vs Fortran arithmetic Keywords: Fortran Message-ID: <9010230628.AA22160@admin.ogi.edu> Date: 23 Oct 90 06:28:24 GMT Sender: compilers-sender@esegue.segue.boston.ma.us Reply-To: John Roberts Organization: Compilers Central Lines: 24 Approved: compilers@esegue.segue.boston.ma.us I know there are differences in IEEE arithmetic and Fortran-77 arithmetic. The IEEE arithmetic is well-defined in the IEEE Standard for binary floating point arithmetic (ANSI standard 754-1985). I presume (but don't know) that the Fortran standard defines Fortran arithmetic precisely. Does anyone know of any references that compare or contrast IEEE 754 floating point arithmetic with other standards, such as Fortran? Thanks! John Roberts robertsj@admin.ogi.edu [You presume far too much, F77 has very little to say about numerical results. The compiler has great freedom to reorganize expressions any way it wants so long as it respect parens. For example, if you write X*A+X*B it may compute X*(A+B) though not the other way around. The standard flatly forbids any expression that causes an exception; all exception handling is a local extension. I know of no reason that an IEEE implementation of F77 would be nonconforming. -John] -- Send compilers articles to compilers@esegue.segue.boston.ma.us {ima | spdcc | world}!esegue. Meta-mail to compilers-request@esegue.