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Have numeric 0 ^ 4.3 return 1, rather than an error, and have 0 ^ 0.0

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return 1, rather than error.

This was already the float8 behavior.
This commit is contained in:
Bruce Momjian 2008-05-08 19:25:38 +00:00
parent eabd1b2ee8
commit 6b4e9d1654
1 changed files with 16 additions and 7 deletions
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23
src/backend/utils/adt/numeric.c
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@ -14,7 +14,7 @@
* Copyright (c) 1998-2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.110 2008/04/21 00:26:45 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.111 2008/05/08 19:25:38 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -5170,6 +5170,21 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
int local_rscale;
double val;
/*
* This avoids log(0) for cases of 0 raised to a non-integer.
* Also, while 0 ^ 0 can be either 1 or indeterminate (error), we
* treat it as one because most programming languages do this.
* http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
*/
if (cmp_var(base, &const_zero) == 0)
{
if (cmp_var(exp, &const_zero) == 0)
set_var_from_var(&const_one, result);
else
set_var_from_var(&const_zero, result);
return;
}
/* If exp can be represented as an integer, use power_var_int */
if (exp->ndigits == 0 || exp->ndigits <= exp->weight + 1)
{
@ -5266,15 +5281,9 @@ power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
NumericVar base_prod;
int local_rscale;
/* Detect some special cases, particularly 0^0. */
switch (exp)
{
case 0:
if (base->ndigits == 0)
ereport(ERROR,
(errcode(ERRCODE_FLOATING_POINT_EXCEPTION),
errmsg("zero raised to zero is undefined")));
set_var_from_var(&const_one, result);
result->dscale = rscale; /* no need to round */
return;