matrix of Ellipsoid multiplied by scalar

Hi guys,

I wanted ask you the following question:

Given a matrix A and a vector c representing a center of an ellipsoid, i need to enlarge the ellipsoid by epsilon so the obvious solution would be multiplying A by (1+epsilon) but when i plot the enlarged ellipsoid i see that it has been shrunk by epsilon not enlarged.

The code that i have used to plot the ellipsoid can be downloaded and seen through the following link:

http://www.mathworks.com/matlabcentral/fileexchange/13844-plot-an-ellipse-in--center-form-

How is this possible? can you explain?

thanks in advance.