RFA: Add definition of M_LOG2_E when compiling in ISO C99 mode

Jeff Johnston jjohnstn@redhat.com
Fri Sep 7 16:02:00 GMT 2007

Nick Clifton wrote:
> Hi Jeff,
>> Thanks Nick for pointing this out.  I have made a patch, slightly 
>> different than yours, that fixes the problem.  Basically, I just 
>> defined a macro _M_LOG2E that is defined regardless.  The macro is 
>> used by log2 and log2f and M_LOG2E uses it as well.
> Ok, but can you enlighten me a little bit please ?  What is the 
> difference between M_LOG2E and M_LOG2_E ?  They are both defined in 
> math.h, but have different values and the log2() and log2f macros 
> which used to use the value of M_LOG2_E now use M_LOG2E.
> Cheers
>   Nick
There are two macros with similar names and different meaning.  One is 
the ln of 2 and the other is the log2 of e.  I had it right but then I 
did a check making sure everything was the same and I thought I had 
inadverently added the underscore between 2 and E.  Thanks for catching 

-- Jeff J.

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