0_0_24855880_214.cpp: In function 'int main()': 0_0_24855880_214.cpp:9:17: error: 'atan' was not declared in this scope n=atan(1/s)-atan(1/u); ^ 0_0_24855880_214.cpp:10:16: error: 'tan' was not declared in this scope v=1/tan(n); ^