View Compilation Error

0_0_5409298_30705.cpp: In function `int main()':
0_0_5409298_30705.cpp:5: error: expected unqualified-id before "double"
0_0_5409298_30705.cpp:5: error: expected `,' or `;' before "double"
0_0_5409298_30705.cpp:11: error: `x1' undeclared (first use this function)
0_0_5409298_30705.cpp:11: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5409298_30705.cpp:11: error: `y1' undeclared (first use this function)
0_0_5409298_30705.cpp:11: error: `x2' undeclared (first use this function)
0_0_5409298_30705.cpp:11: error: `y2' undeclared (first use this function)
0_0_5409298_30705.cpp:11: error: `x3' undeclared (first use this function)
0_0_5409298_30705.cpp:11: error: `y3' undeclared (first use this function)
0_0_5409298_30705.cpp:12: error: `a' undeclared (first use this function)
0_0_5409298_30705.cpp:13: error: `b' undeclared (first use this function)