pascal complex var operations

complex

{complex var operations}
procedure cmul(a,b:complex; var c:complex);
begin
c.x := a.x * b.x - a.y * b.y;
c.y := a.x * b.y + b.x * a.y;
end;

procedure csum(a,b:complex; var c:complex);
begin
c.x := a.x + b.x;
c.y := a.y + b.y;
end;

procedure cdiv(a,b:complex; var c:complex);
begin
c.x := (a.x*b.x + a.y*b.y) / (b.x*b.x + b.y*b.y);
c.y := (b.x*a.y - a.x*b.y) / (b.x*b.x + b.y*b.y);
end;

procedure csqr(a:complex; var c:complex);
begin
cmul(a,a,c);
end;