View Compilation Error

0_0_6821490_32439.cpp: In function `int main()':
0_0_6821490_32439.cpp:55: error: `fabs' undeclared (first use this function)
0_0_6821490_32439.cpp:55: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6821490_32439.cpp:55: error: `eps' undeclared (first use this function)