Hi everyone,
I believe that there is a small bug in src/port/rint.c when the input
parameter has a fractional part of 0.5 which is demonstrated by the
attached program. It appears that the PG version of rint() rounds in the
wrong direction with respect to glibc.
[EMAIL PROTECTED]:~$ ./test
rint(-1.5): -2.000000
pg_rint(-1.5): -1.000000
rint(1.5): 2.000000
pg_rint(1.5): 1.000000
The fix is, of course, to add an equals into the if() comparisons on
lines 21 and 26, so that when the fractional part is 0.5, it rounds in
the opposite direction instead.
I'm sure that this will have practically zero effect on the code,
however it may be worth applying for correctness and consistency with
other platform implementations.
ATB,
Mark.
--
ILande - Open Source Consultancy
http://www.ilande.co.uk
/*
* rint() test program
*
* Compile on gcc using:
* gcc -o test test.c -lm
*/
#include <math.h>
#include <stdio.h>
double
pg_rint(double x)
{
double f,
n = 0.;
f = modf(x, &n);
if (x > 0.)
{
if (f > .5)
n += 1.;
}
else if (x < 0.)
{
if (f < -.5)
n -= 1.;
}
return n;
}
int main()
{
printf("rint(-1.5): %f\n", rint(-1.5));
printf("pg_rint(-1.5): %f\n", pg_rint(-1.5));
printf("rint(1.5): %f\n", rint(1.5));
printf("pg_rint(1.5): %f\n", pg_rint(1.5));
}
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