View Compilation Error

0_0_9762650_7049.cpp: In function `double dis1(all)':
0_0_9762650_7049.cpp:11: error: `returnsqrt' undeclared (first use this function)
0_0_9762650_7049.cpp:11: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9762650_7049.cpp: In function `double dis2(all, all)':
0_0_9762650_7049.cpp:15: error: `returnsqrt' undeclared (first use this function)