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

If I were you I would print it with more digits so you see if there is any significant 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

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

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.

Hi faber,

well, even mathematically, it is sorta right... yes the sin(0)=0 but looking at its graph, it is a rising slope, so sin(x near to 0-) < 0 :)

:)
L.