[fpc-pascal] Sin function
Hi, according to docs/reference sin function should print 0.0 when Writeln (Sin(Pi):0:1); but, with fpc 2.4.0 and 2.4.2 (x86) I've get -0.0, such a result is not entirely correct. This is a bug (in sin func.) or something wrong with the formatting ? best regards faber ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] Sin function
faber bor...@gmail.com wrote: Hi, according to docs/reference sin function should print 0.0 when Writeln (Sin(Pi):0:1); but, with fpc 2.4.0 and 2.4.2 (x86) I've get -0.0, such a result is not entirely correct. This is a bug (in sin func.) or something wrong with the formatting ? best regards faber If I were you I would print it with more digits so you see if there is any significant difference at all. /Ingemar ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Sin function
If I were you I would print it with more digits so you see if there is any significant difference at all. ok I understand, I was suggested by http://www.freepascal.org/docs-html/rtl/system/sin.html where it is given score 0.0 for Writeln (Sin(Pi):0:1); best regards faber ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Sin function
Hi Ingemar 0.0 and -0.0 is the same number ;) it's just a quirk of the IEEE floating point format, that there exists a positiv and negative zero (because they use a sign bit). -Ivo Am 29.12.2010 12:17, schrieb Ingemar Ragnemalm: faber bor...@gmail.com wrote: Hi, according to docs/reference sin function should print 0.0 when Writeln (Sin(Pi):0:1); but, with fpc 2.4.0 and 2.4.2 (x86) I've get -0.0, such a result is not entirely correct. This is a bug (in sin func.) or something wrong with the formatting ? best regards faber If I were you I would print it with more digits so you see if there is any significant difference at all. /Ingemar ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Sin function
faber wrote: If I were you I would print it with more digits so you see if there is any significant difference at all. ok I understand, I was suggested by http://www.freepascal.org/docs-html/rtl/system/sin.html where it is given score 0.0 for Writeln (Sin(Pi):0:1); Transcendentals are a can of worms. Without and with formatting respectively, ARM, PowerPC, SPARC: 1.22464706384516E-016 0.0 x86 (P-III): -5.4210108624275222E-0020 -0.0 All FPC 2.4.2 on Linux. The result /should/ be zero, and x86- which I presume is what you're running- is nearer zero than the others :-) There are lots of issues here, including the number of bits used internally by the floating point hardware and whether it knows Pi to this degree of precision. Also it might depend on optimisation level etc. -- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues] ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
