GCC:- Some warnings I do not understand.

[Phil Prentice]

Hi 
   I am using gcc to compile some 'c' code (with the -traditional flag being set) and I am getting the following warning.

  filename.c:46: warning: conflicting types for built-in function cosf.

  The line that cause this is

  extern float cosf();

  I was wondering if you could help me as to why am I getting this warning and what is the best way of getting rid of it?

  Thanks
     Phil
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