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Xref: | news2.mv.net comp.lang.c:54819 comp.lang.c++:70367 comp.os.msdos.djgpp:740 gnu.g++.help:4477 gnu.gcc.help:5678 |
From: | axl AT zedat DOT fu-berlin DOT de (Axel Thimm) |
Newsgroups: | comp.lang.c,comp.lang.c++,gnu.gcc.help,gnu.g++.help,comp.os.msdos.djgpp |
Subject: | Re: float != float and floats as return types |
Date: | Fri, 02 Feb 1996 03:31:08 GMT |
Organization: | FU Berlin |
Lines: | 26 |
Message-ID: | <4es0ep$is2@fu-berlin.de> |
References: | <DM19oy DOT KsJ AT granite DOT mv DOT net> |
Reply-To: | axl AT zedat DOT fu-berlin DOT de |
NNTP-Posting-Host: | axl.dialup.fu-berlin.de (160.45.218.93) |
To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote: [...] >> -ffloat-store >Just to make the picture complete: this switch should only be used in >programs which break without it, because holding intermediate results in >the most precise representation makes FP computations more accurate. [...] >Another case of justified use of that switch is a program which explores >the intricacies of the floating-point representation of a machine. The reason I "expored" this behaviour was an optimization by hand of a simulation program. A lattices site value is very often used in quadratic terms, so introducing a second lattice and storing theese values seemed like just speeding up the process. I was amazed when the output changed (the results were still within the stat. error). So if someone is writing programs that can do exactly the same thing with two different implementations, then he would very much like to turn such optimizations temporarily off, to get the same results. Later he would turn them on again. === Axel Thimm <axl AT zedat DOT fu-berlin DOT de> Freie Universitaet Berlin ===
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