View Compilation Error

0_0_27192164_24957.c:4:8: error: conflicting types for 'abs'
 double abs(double a){
        ^
In file included from 0_0_27192164_24957.c:2:0:
GCC4.9.2/x86_64-w64-mingw32/include/math.h:205:15: note: previous declaration of 'abs' was here
   int __cdecl abs(int _X);
               ^