xs= -2:0.05:2
ys=1 ./ (xs.^2+1);
using PyPlot
plot(xs,ys)
x0=-0.2
ys=1 ./ ((xs-x0).^2+1);
plot(xs,ys)
x0=-0.2
gamma=3
ys=gamma ./ ((xs-x0).^2+gamma^2);
plot(xs,ys)