[Haskell-cafe] Re: Is logBase right?

Ketil Malde ketil at malde.org
Tue Aug 25 13:11:18 EDT 2009


Steve <stevech1097 at yahoo.com.au> writes:

> Also, I had a problem using floating point in Python where
>>>> round(697.04157958254996, 10)
> gave
> 697.04157958259998  

> Its been fixed in the latest versions of Python:
>>>> round(697.04157958254996, 10)
> 697.0415795825

> ghci> roundN 697.04157958254996 10   
> 697.0415795826

Is there something special with this number?

  Python 2.6.2 (release26-maint, Apr 19 2009, 01:56:41) 
  [GCC 4.3.3] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  >>> 697.04157958259998
  697.04157958259998
  >>> 12345.678901234567890
  12345.678901234567

  GHCi, version 6.8.2: http://www.haskell.org/ghc/  :? for help
  Loading package base ... linking ... done.
  Prelude> 697.04157958259998
  697.0415795826
  Prelude> 12345.678901234567890
  12345.678901234567

So, Python manages to keep more decimals than GHC for your number, but
for other numbers, the precision appears to be the same.

-k
-- 
If I haven't seen further, it is by standing in the footprints of giants


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