Public bug reported:
sinl fails to return a correct result for large arguments.
Consider the following file:
$ cat sintest.c
#include <stdio.h>
#include <math.h>
int
main (void) {
double arg = 1e22;
long double larg = 1e22L;
printf("double precision: sin(1e22) = %.16lf\n", sin(arg));
printf("quad precison: sin(1e22)=%.16Lf\n", sinl(larg));
return 0;
}
when compiled by gcc
$ gcc sintest.c -lm
it produces wrong results
$ ./a.out
double precision: sin(1e22) = -0.8522008497671888
quad precison: sin(1e22)=0.4626130407646018
This problem is probably due to the use of 'fsin' function which does
not support such a big number. However, from the description of 'sinl'
one would expect full support for long double arguments.
P.S.
The same code compiled by the Intel C compiler produces good results.
ProblemType: Bug
Architecture: amd64
Date: Thu Mar 18 11:01:02 2010
DistroRelease: Ubuntu 9.10
Package: libc6 2.11.1-0ubuntu4
ProcEnviron:
PATH=(custom, user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-16.25-generic
SourcePackage: eglibc
Uname: Linux 2.6.32-16-generic x86_64
** Affects: eglibc (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug
--
sinl (and probably other functions) is not computed correctly
https://bugs.launchpad.net/bugs/540771
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