Undefined symbol 'atan2' in file 'filename.o' After that i have added the corresponding library function in linker options (libm.a) to avoid this problem. I got rid of above probelm, but i am facing some other problem which is also pasated below. Undefined symbol '__errno_fn' in file 'atan2.o(C:\diab\5.2.1.0\PPCEH\libm.a I am unable to resolve the above problem. Can u please provide me the solution to avoid the above problem