How to find the intersection point by plotting the red line like below?

how to add line and find y value like this if x is 0.1? like this

thanks

Answer 1

[Jon]

Assuming you have the water level in a vector, lets call it h, along with the values of pExceed in another vector, you can interpolate to estimate the level when pExceed equals 0.1

Somthing like

hInterp = interp1(pExceed,h,0.1);

You could then plot the data

plot(pExceed,h,'-b',0.1,hInterp,'*r')

If you want the horizontal and vertical red line you can plot the box with a bar plot, so

plot(pExceed,h,'-b',0.1,hInterp,'*r')
hold on
% make a single bar, bar is centered midway between 0 and 0.1 and has a width of 0.1 to get
% the effect you want
bar(0.1/2,hInterp,0.1,'FaceColor','none','EdgeColor','red')
hold off