clear; clf;
hold on
alpha=1/(2*2);
nx=100;
x=linspace(-1.5,1.5,nx);
m=2;
F=alpha*(x.^m-1).^2;
plot(x,F,'k','linewidth',1.5);
m=4;
F=alpha*(x.^m-1).^2;
plot(x,F,'ko-','linewidth',0.5);
m=6;
F=alpha*(x.^m-1).^2;
plot(x,F,'k*-','linewidth',0.5);
m=20;
F=alpha*(x.^m-1).^2;
plot(x,F,'kd-','linewidth',0.5);

axis([x(1) x(end) -0.01 0.5])
legend1=legend('$$m=~ 2$$','$$m=~4$$','$$m=~6$$','$$m=20$$');
set(legend,'Interpreter','latex','fontsize',17)
text('Interpreter','latex','String','$$ \phi $$','Position',[0.75 -0.045],'fontsize',17);
text('Interpreter','latex','String','$$ F(\phi) $$','Position',[-1.85 0.45],'fontsize',17);
set(gca,'fontsize',17) 
set(legend1,...
    'Position',[0.4158 0.6389 0.2210 0.2721],'Interpreter','latex','FontSize',17);
set(gcf,'PaperPositionMode','auto')