fill problem--shading the wrong parts of a curve

I'm having trouble using fill to shade the area between two curves. The code I'm using is

fill(x,[y1 y2],'k')

I've also tried

fill([x x],[y1 y2],'k')

which gives the same result. Is there something obvious I'm missing? Below is the plot I'm getting. I'd like to shade the are between the two curves, not between the first and last y value of each curve. Ideas?

Answer 1

[Sean de Wolski]

And there is a problem we all run into the first time we use fill() :)

x = 1:10;
y1 = rand(1,10)+1;
y2 = rand(1,10)-0.5;
fill([x fliplr(x)],[y1 fliplr(y2)],'c')

The sorting order is important. You want to trace the outside as if you were to walk around your x/y coordinates.

[Chad Greene]

Brilliant! The "walking the perimeter" explanation is exactly what I was missing.

For my columns of data I had to make a little tweak, but that was easy now that I understand how it works.

fill([x;flipud(x)],[y1;flipud(y2)],'k')

Thank you for your help!