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Add regression test for various power expressions with a zero base, and

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adjust source code to be more modular.
This commit is contained in:
Bruce Momjian 2008-05-08 22:17:54 +00:00
parent 6b4e9d1654
commit 4a586bd405
3 changed files with 25 additions and 16 deletions
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33
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 1.111 2008/05/08 19:25:38 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.112 2008/05/08 22:17:54 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -5170,21 +5170,6 @@ 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)
{
@ -5217,6 +5202,17 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
free_var(&x);
}
/*
* This avoids log(0) for cases of 0 raised to a non-integer.
* 0 ^ 0 handled by power_var_int().
*/
if (cmp_var(base, &const_zero) == 0)
{
set_var_from_var(&const_zero, result);
result->dscale = NUMERIC_MIN_SIG_DIGITS; /* no need to round */
return;
}
init_var(&ln_base);
init_var(&ln_num);
@ -5284,6 +5280,11 @@ power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
switch (exp)
{
case 0:
/*
* While 0 ^ 0 can be either 1 or indeterminate (error), we
* treat it as 1 because most programming languages do this.
* http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
*/
set_var_from_var(&const_one, result);
result->dscale = rscale; /* no need to round */
return;

6
src/test/regress/expected/float8.out
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@ -349,6 +349,12 @@ SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
ERROR: value out of range: overflow
SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
ERROR: value out of range: overflow
SELECT 0 ^ 0 + 0 ^ 1 + 0 ^ 0.0 + 0 ^ 0.5;
?column?
----------
2
(1 row)
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 = '0.0' ;
ERROR: cannot take logarithm of zero
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 < '0.0' ;

2
src/test/regress/sql/float8.sql
View File

@ -129,6 +129,8 @@ SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
SELECT 0 ^ 0 + 0 ^ 1 + 0 ^ 0.0 + 0 ^ 0.5;
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 = '0.0' ;
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 < '0.0' ;