Algorithm Math Delphi

Title: Determine the Circumcenter of a triangle
Procedure Circumcenter(x1,y1,x2,y2,x3,y3:Double; Var Px,Py:Double);
Var A,C,B,D,E,F,G:Double;
Begin
A := x2 - x1;
B := y2 - y1;
C := x3 - x1;
D := y3 - y1;
E := A*(x1+x2)+B*(y1+y3);
F := C*(x1+x2)+D*(y1+y3);
G := 2.0*(A*(y3-y2)-B*(x3-x2));
If G = 0 Then Exit;
Px:=(D*E - B*F)/G;
Py:=(A*F - C*E)/G;
End;
(* End Of Circumcenter *)