How to find the angle made by eigen vector and x-axis?

I have used the function "eig()" to obtain eigen values and eigen vectors of a grayscale image, i now need to find the angle made by the eigen vector with respect to x-axis. Please help!

Thanks in advance!

[Geoff Hayes]

Can't the usual method of finding the angle be used? If the vector is [x1 y1], then the angle with respect to the x-axis is atan2(y1,x1)? (Naturally this assumes an origin of (0,0) which may be different than that which is in your problem.)

[John D'Errico]

We don't know how you used eig in this case. For example, did you simply apply eig to a square image as an array? Show what you did, as your question is impossible to answer otherwise.