How to create an off-center, rotated, cosine-ramped edged ellipse?

Hi all,

I'm trying to make an off-center, rotated, cosine-ramped edged ellipse. Managed to make it off-center and cosine-ramped the edges, but I'm having difficulties trying to rotate it. Here's my code so far:

 imSize =128;
 width=10;
 height=20;
 aspectRatio=width/height;
 nCosSteps=5;

 [X,Y]= meshgrid((-imSize/2+1:imSize/2),(-imSize/2+1:imSize/2));

 radii = sqrt((X-centerX).^2 + ((Y-centerY)*aspectRatio).^2);

 %%%set inner edge to zero

 radii = radii - radii(floor(end/2)+centerX+floor(apWidth/2)
- nCosSteps,floor(end/2)+centerY+floor(apHeight/2)-nCosSteps);

 %%%Do linear transform to set outer edge to pi

 outerVal = radii(end/2+centerX+floor(apWidth/2)-1,
end/2+centerY+floor(apHeight/2)-1);

 radii = radii * pi/outerVal ;

 % set more central values 0 (ie, cos(0) = 1)

 radii( find(radii<=0) ) = 0;

 % set values more beyond steps to pi (ie, cos(pi) = 0)

 radii( find(radii>=pi) ) = pi;    

 % Take cos of all the transformed radial values.

 raisedCosMask = .5 + .5 * cos(radii);

 if mod(imSize,2) == 1% odd number
    raisedCosMask = raisedCosMask(1:end-1,1:end-1);
 end

And this gives:

How should I proceed to rotate this ellipse (i.e., angles like 45 degrees, 20 degrees)? Any help would be greatly appreciated! :)