hello
do you mean the last plot ?
here a simple code that replicate it : (there is still a bit of work if you want all the details )
y= linspace(0,1.22,100);
E = y+0.051./y.^2;
plot(y,y,'k--'); % diagonal
hold on
plot(E,y,'b','linewidth',2);
xlabel('E')
ylabel('y')
grid on
hold off
xlim([0 1.83])
