Re: [HACKERS] regression bigtest needs very long time

Hi,

wieck@debis.com (Jan Wieck) wrote:
> 
>     The  complex  functions  (LN,  LOG, EXP, etc.) where added to
>     NUMERIC for the case someone really  needs  higher  precision
>     than  float8.   The  numeric_big  test  simply  ensures  that
>     someone really get's the  CORRECT  result  when  computing  a
>     logarithm  up to hundreds of digits. All the expected results
>     fed into the tables are computed by scripts using bc(1)  with
>     a  precision  200  digits  higher  than that used in the test
>     itself. So I'm  pretty  sure  NUMERIC  returns  a  VERY  GOOD
>     approximation  if  I  ask  for the square root of 2 with 1000
>     digits.
  I was able to understand the specification for the NUMERIC 
data type. But, I can not yet understand the specification of 
the regression normal test.
  File     :"src/regress/sql/numeric.sql"  Function : LN(ABS(round(val,300)))           ---->  LN(ABS(round(val,30)))
<----My hope
 
  Please teach me, 
  Is there a difference of the calculation algorithm between 30 
and 300 digits ?
  Is there a difference of something like CPU-dependence or like
compiler-dependence between 30 and 300 digits ?


# If the answer is "NO", I think that the 300 digits case is  not necessary once you are sure that it works,  because 
 1. the 30 digits case is equivalent to the 300 digits case. 2. the 300 digits case is slow. 3. It is sufficiently
largevalue even in 30 digits.  
 

--
Regards.

SAKAIDA Masaaki <sakaida@psn.co.jp>
Osaka, Japan