Help with 'underwater' plot

I'm trying to create a so-called underwater plot for a time series ts, where all of the points that follow the most recent local maximum should be below an even water surface:

But if you take a closer look at my plot, you can see that some of the water surfaces actually have an unusual bump on the right side. I can't figure out why my code creates these bumps and how to avoid that. Any help would be appreciated..

Here's my code:

for i = 1:length(ts),
    water(i) = max(ts(1:i));
end
area(water,'FaceColor',[0.04,0.52,0.78]);
hold on; 
area(ts,'FaceColor',[0.68,0.47,0]);

[Sean de Wolski]

Can you post the example data set as a ZIP file?

[dave]

Sean, ts is just an artificial time series. I generated it like this:

ts = cumsum(randn(100,1));

Answer 1

[Walter Roberson]

At the point where the time series increases, max(ts(1:i)) is going to assume the new higher value. This is going to be connected to the previous max(ts(1:i-1)) that was the lower peak. So you have plot([y1 y2]) where y2 > y1, and that is going to be joined as a linear interpolation.

Answer 2

[Image Analyst]

Those are just the prior element. If you plot with markers, you'll see that it's merely drawing a straight line from the prior element to the new, higher element. If you want to make that smaller, you'll have to make the x axis have at least as many elements as pixels across in your plot. So, like if ts is 100 elements, make it 1000 elements and those "bumps" will be narrower.

[dave]

I see, thanks..