Solve x^T M x + x^T N \dot{x}=0

Hello,

I need to find M and N of

x^T M x + x^T N \dot{x}=0

I have samples of x and \dot{x}, and I need to approximate M and N.

Is there a method in Matlab that allows me to solve this problem?

Thanks

[Torsten]

What about M = N = 0 ?

What I want to say is:

Are there any conditions on M and N that prevent the trivial solution ?

Best wishes

Torsten.