// --------------
//  The G series
// --------------
height=400;
width =400;
clip=none;
clear_screen;
curve = -(y+x+x*y)*(12*(y+x+x*y)^7*(1+x+y)*x*y
        -256*(1+x+y)^2*(y+x+x*y)^2*x^4*y^4
        +384*(1+x+y)*(y+x+x*y)*x^5*y^5
        -64*(y+x+x*y)^3*x^4*y^4-12*(y+x+x*y)^6*x^2*y^2
        -192*x^6*y^6+64*(1+x+y)^3*(y+x+x*y)^3*x^3*y^3
        +112*(y+x+x*y)^4*(1+x+y)*x^3*y^3
        -48*(y+x+x*y)^5*(1+x+y)^2*x^2*y^2-(y+x+x*y)^9);
draw_curve;