Here are few equations I am using now. if you guys need I can provide a link to plot each of these graphs. The plotting program I am using allow to use up to 3 different function same time.

(1) sin(pi*x/5)-tan(x*2)

(2) min(sin(pi*x-2),0.452)

(3) F1::cos(pi*x) / (-ln(2)*x), F2::sqrt(9-x^2), F3::-sqrt(9-x^2)

(4) F1::x*sin(10*x), F2::x, F3::-x

(5) F1::ln(x)*cos(15*x), F2::ln(x), F3::-ln(x)

(6) sin(954*x)-2*cos(x)

Thanks in advance