V8/usr/lib/ideal/lib/CIRCLE

.IS
CIRCLE {
	var rad;
	z1 ~ z2 ~ z3 ~ center + rad;
	var a1, b1, c1,
	a2, b2, c2;
	a1 = 2*(re(z2)-re(z1));
	b1 = 2*(im(z2)-im(z1));
	c1 = -re(z1)*re(z1) - im(z1)*im(z1) + re(z2)*re(z2) + im(z2)*im(z2);
	a2 = 2*(re(z3)-re(z2));
	b2 = 2*(im(z3)-im(z2));
	c2 = -re(z2)*re(z2) - im(z2)*im(z2) + re(z3)*re(z3) + im(z3)*im(z3);
	a1*re(center) + b1*im(center) = c1;
	a2*re(center) + b2*im(center) = c2;
	radius = abs(rad);
	rad ~ radius;
}
.IE