How do I plot an animated vertical line?

I want to graph the motion of a diver swimming straight downwards to the sea floor at an x position of 20,000 feet from the origin, touching it the sea floor, then immediatelely ascending directly upward.

In my case, the x-axis represents horizontal distance [0, 20000] and the y-axis is depth [0, -1000]. I want use an overlay plot where both the shark's and diver's motion are animated simultaneously. I have approached it from many directions but have not been able to animate the diver's motion.

What command should I use to illustrate the diver while the shark is swimming towards his boat at the surface?

clc, clear

%Here is the motion of the shark, swimming horizontally towards the diver's boat which is 20k feet away.
x1 = [0:1:20000];
y1 = 0*x1+0;

ax=axes;
title('Shark Motion and Diver Motion')
xlabel('Depth (Feet)')
ylabel('Horizontal Position (Feet)')
grid on
set(ax,'xlim',[0 20000],'ylim',[-1000 0]);
hold (ax);
comet(x1,y1);

%Here is the motion of the diver, swimming from the surface of the water
%straight down 1000 feet to the sea floor, then immediately swimming updard at the
%same speed.
x2 = [0:1:20000]
y2 = 0*x1+0;
set(ax,'xlim',[0 20000],'ylim',[0 -1000]);
comet(x2,y2);

%What command should I use to animate the diver's vertical motion as the
%shark approaches? I cannot get 'comet' to work.

[DERYA DILMEN]

Check out this answer in mathworks :

https://fr.mathworks.com/matlabcentral/answers/295622-axes-with-moving-vertical-line

Answer 1

[Cris LaPierre]

You cannot have two 'comets' running at the same time using comet. You could look into using this function from the file exchange.

Additional comments:

• Your code is throwing an error about the second 'set' command. The order of your YLim needs to be switched.
• You only need to set the axis limits once, so the second one is actually not necessary