Re: Regression error on float8

> > What do you think is best - try to adapt that version, or
> update our
> > regression tests outputs to accept the output from our current code?
>
> Given that our output gets very very close, perhaps we should
> take a hint from the end of the MinGW version, do a single
> Newton iteration to fixup those last few digits.
>
> Adding this before the last line of our version of cbrt():
>
> tmpres -= ( tmpres - (x/(tmpres*tmpres)) )*0.33333333333333333333;
>
> Makes it give the same result as my system version...

That totally didn't work on visual c++ at least. It fixes those two
ones, but it breaks the other lines in the same test:

*** ./expected/float8-exp-three-digits-win32.out Wed Jun 8
23:15:29 2005
--- ./results/float8.out Mon Apr 24 21:57:40 2006
***************
*** 321,329 ****
SELECT '' AS five, f.f1, ||/f.f1 AS cbrt_f1 FROM FLOAT8_TBL f;
five | f1 | cbrt_f1
------+----------------------+-----------------------
! | 0 | 0
| 1004.3 | 10.014312837827
! | -34.84 | -3.26607421344208
| 1.2345678901234e+200 | 4.97933859234765e+066
| 1.2345678901234e-200 | 2.3112042409018e-067
(5 rows)
--- 321,329 ----
SELECT '' AS five, f.f1, ||/f.f1 AS cbrt_f1 FROM FLOAT8_TBL f;
five | f1 | cbrt_f1
------+----------------------+-----------------------
! | 0 | NaN
| 1004.3 | 10.014312837827
! | -34.84 | -1.08869140448069
| 1.2345678901234e+200 | 4.97933859234765e+066
| 1.2345678901234e-200 | 2.3112042409018e-067
(5 rows)

//Magnus