PSplot plot1=new PSplot(pg,100.,500.,100.,500.);
plot1.setlimits(0.,5.,0.,1.);
plot1.frame();
plot1.autoscales();
plot1.xlabel("abscissa");
plot1.ylabel("ordinate");
plot1.lineplot(x1,y1);
plot1.setdash("2 4");
plot1.lineplot(x1,y2);
plot1.setdash("6 2 4 2");