Thank you for your help.
Let me try what you suggested.
Regarding eig function.... actually Rxx is calculated by the function of another variable.
Both Mathscript and Matlab calculated same Rxx, but they produced totally different value of x and y. They are not even similar.
I have to use x value in next stage.
The result is totally different due to different value of eig function.
I really don't understand why they produced different values.
Many thanks.
