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Update pow() tests to check for both errno==EDOM _and_ result==Nan, and 

document why this happens.  Remove exp() errno check because not needed.
This commit is contained in:
Bruce Momjian 2007-01-03 22:05:00 +00:00
parent 812095d604
commit 9c88830ec4
1 changed files with 12 additions and 18 deletions
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30
src/backend/utils/adt/float.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.138 2007/01/03 19:34:23 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.139 2007/01/03 22:05:00 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -1440,17 +1440,24 @@ dpow(PG_FUNCTION_ARGS)
/*
* pow() sets errno only on some platforms, depending on whether it
* follows _IEEE_, _POSIX_, _XOPEN_, or _SVID_, and some return Nan,
* so we check and set result properly.
* follows _IEEE_, _POSIX_, _XOPEN_, or _SVID_, so we try to avoid
* using errno. However, some platform/CPU combinations return
* errno == EDOM and result == Nan, so we have to check for that and
* set result properly. For example, Linux on Pentium, pre-Xeon
* hardware returns EDOM/Nan for (-1) ^ 1e19, but (-1) ^ 1e18 retuns
* 1 -- basically a negative base raised to a very high power causes
* it on some CPUs.
*/
errno = 0;
result = pow(arg1, arg2);
if (errno == ERANGE || isnan(result))
if (errno == EDOM && isnan(result))
{
if ((fabs(arg1) > 1 && arg2 >= 0) || (fabs(arg1) < 1 && arg2 < 0))
result = (arg1 >= 0) ? get_float8_infinity() : -get_float8_infinity();
else
else if (fabs(arg1) != 1)
result = 0;
else
result = 1;
}
CHECKFLOATVAL(result, isinf(arg1) || isinf(arg2), arg1 == 0);
@ -1467,20 +1474,7 @@ dexp(PG_FUNCTION_ARGS)
float8 arg1 = PG_GETARG_FLOAT8(0);
float8 result;
/*
* exp() sets errno only on some platforms, depending on whether it
* follows _IEEE_, _POSIX_, _XOPEN_, or _SVID_, and some return Nan,
* so we check and set result properly.
*/
errno = 0;
result = exp(arg1);
if (errno == ERANGE || isnan(result))
{
if (arg1 >= 0)
result = get_float8_infinity();
else
result = 0;
}
CHECKFLOATVAL(result, isinf(arg1), false);
PG_RETURN_FLOAT8(result);