How can I show the maximum in my graphs?

Hi guys,

I got the maximum of y4, but I don't know how to show it in my graphs.

   clear all
close all
x=(0:0.01:80).';
y1=(0.02049/0.4)*x;
y2=(0.53*60./(1+(1.331./(sqrt(0.0631*x./(83.18-x))).^3)));
y3=(0.53*60./(1+(1.331./(sqrt(0.0631*x./(83.18-x))).^3)))-(0.02049/0.4)*x;
y4=(0.02049/0.4)*x-(0.53*60./(1+(1.331./(sqrt(0.0631*x./(83.18-x))).^3)));
figure
plot(x,y1,'r')
hold on 
plot(x,y2,'c')
plot(x,y3,'g')
plot(x,y4,'b')
legend('Line1','Line2','Line3','Line4')
axis([0 80 -1 3.5])
x=linspace(0, 80, 200);
y4=@(x) (0.02049/0.4)*x-(0.53*60./(1+(1.331./(sqrt(0.0631*x./(83.18-x))).^3)));
f = y4(x);
[y4Max, iMax] = max(f)
xMax = x(iMax)

Thank you very much

Answer 1

[the cyclist]

Do you mean like this?

line([xMax xMax],ylim)

[Mo_B]

Thanks a lot, do you know a way to stop the vertical line when it hits the function? And display the x-value?

[the cyclist]

y_lim = ylim;
line([xMax xMax],[y_lim(1) y4Max])
text(xMax,y4Max+0.1,'Wheeee!')