Is a Curved Gradient Possible?

I made a rectangle with a curved top.
I need the gradient to curve like to top does…

I want that gradient to be close to top… and curved just like to top…

Anyone know if that is possible?

I am starting to think it is not…

Here is the image:
http://www.videolinktechnologies.com/curve.gif

<img src=“http://www.videolinktechnologies.com/curve.gif”>