Alvaro Herrera wrote: > Bruce Momjian wrote: > > Tom Lane wrote: > > > Bruce Momjian <[EMAIL PROTECTED]> writes: > > > > I have developed the attached patch which fixes 0 ^ 123.3. > > > > > > Did you actually read the wikipedia entry you cited? > > But that's about 0^0, not about 0^123.3. See this other subsection: > > http://en.wikipedia.org/wiki/Exponentiation#Powers_of_zero > > 0^123.3 is 0, not 1.
Ah, got it, and I updated the patch to remove the commment about "discrete". -- Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. +
Index: src/backend/utils/adt/numeric.c =================================================================== RCS file: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v retrieving revision 1.110 diff -c -c -r1.110 numeric.c *** src/backend/utils/adt/numeric.c 21 Apr 2008 00:26:45 -0000 1.110 --- src/backend/utils/adt/numeric.c 7 May 2008 23:18:31 -0000 *************** *** 5170,5175 **** --- 5170,5190 ---- 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) { *************** *** 5266,5280 **** 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; --- 5281,5289 ----
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