View Compilation Error

0_0_24516411_29420.cpp: In function 'double SPIA(Point*, Point*, int, int)':
0_0_24516411_29420.cpp:142:28: error: 'aPolygonArea' was not declared in this scope
     return aPolygonArea(p,n) + PolygonArea(q,m) - area;
                            ^