[Haskell-cafe] Is logBase right?

[Roberto]

Hi, 

There is a mistake is logBase:

$ ghci
GHCi, version 6.10.4: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
Prelude> logBase 10 10
1.0
Prelude> logBase 10 100
2.0
Prelude> logBase 10 1000
2.9999999999999996                  <--- eeeerrgghhhh!
Prelude> logBase 10 10000
4.0


My host is a Debian GNU/Linux 5.0.2 (lenny) with the following GHC packages:

ii  ghc6                                 6.10.4-1                       
ii  ghc6-doc                             6.10.4-1                      
ii  libghc6-mtl-dev                      1.1.0.2-7+b1                  
ii  libghc6-utf8-string-dev              0.3.5-1+b1                    
ii  libghc6-x11-dev                      1.4.5-6                       
rc  libghc6-x11-doc                      1.4.2-1                       
ii  libghc6-x11-xft-dev                  0.3-3+b3                      
ii  libghc6-xmonad-contrib-dev           0.8.1-3+b3                    
rc  libghc6-xmonad-contrib-doc           0.8-2                         
ii  libghc6-xmonad-dev                   0.8.1-5                       

Regards!