View Compilation Error

0_0_6766332_27825.cpp: In function `void init()':
0_0_6766332_27825.cpp:136: error: `atan2' undeclared (first use this function)
0_0_6766332_27825.cpp:136: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6766332_27825.cpp:142: error: `acos' undeclared (first use this function)