Issues with area function to fill under plot

Question

simplified 2017-10-19

回答： Star Strider 2017-10-19

Consider the following code:

xData = rand(100,1)*0.5;
yData = linspace(2000,2500,100);
figure(1)
plot(xData,yData)

which produce the following figure (after resizing it slightly horizontally):

Now, I want to basically fill the area under the curve, i.e. between x=0 and the curve. So, when I try the area function:

figure(2)
area(xData,yData)

I get the following figure (which is obviously not what I want):

What am I doing wrong?

Answer 1

Star Strider 2017-10-19

Try this:

y = 0:20;
x = rand(size(y));
figure(1)
plot(x, y)
hold on
patch([ zeros(size(x)) x ], [ fliplr(y) y ], 'g')
hold off