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Commit6b4e9d1

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Have numeric 0 ^ 4.3 return 1, rather than an error, and have 0 ^ 0.0
return 1, rather than error.This was already the float8 behavior.
1 parenteabd1b2 commit6b4e9d1

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1 file changed

+16
-7
lines changed

1 file changed

+16
-7
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‎src/backend/utils/adt/numeric.c

Lines changed: 16 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@
1414
* Copyright (c) 1998-2008, PostgreSQL Global Development Group
1515
*
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* IDENTIFICATION
17-
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.110 2008/04/21 00:26:45 tgl Exp $
17+
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.111 2008/05/08 19:25:38 momjian Exp $
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*
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*-------------------------------------------------------------------------
2020
*/
@@ -5170,6 +5170,21 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
51705170
intlocal_rscale;
51715171
doubleval;
51725172

5173+
/*
5174+
*This avoids log(0) for cases of 0 raised to a non-integer.
5175+
*Also, while 0 ^ 0 can be either 1 or indeterminate (error), we
5176+
*treat it as one because most programming languages do this.
5177+
*http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
5178+
*/
5179+
if (cmp_var(base,&const_zero)==0)
5180+
{
5181+
if (cmp_var(exp,&const_zero)==0)
5182+
set_var_from_var(&const_one,result);
5183+
else
5184+
set_var_from_var(&const_zero,result);
5185+
return;
5186+
}
5187+
51735188
/* If exp can be represented as an integer, use power_var_int */
51745189
if (exp->ndigits==0||exp->ndigits <=exp->weight+1)
51755190
{
@@ -5266,15 +5281,9 @@ power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
52665281
NumericVarbase_prod;
52675282
intlocal_rscale;
52685283

5269-
/* Detect some special cases, particularly 0^0. */
5270-
52715284
switch (exp)
52725285
{
52735286
case0:
5274-
if (base->ndigits==0)
5275-
ereport(ERROR,
5276-
(errcode(ERRCODE_FLOATING_POINT_EXCEPTION),
5277-
errmsg("zero raised to zero is undefined")));
52785287
set_var_from_var(&const_one,result);
52795288
result->dscale=rscale;/* no need to round */
52805289
return;

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