Hi everybody,

I’m just looking for a clear answer or a reference that gives a demonstration on this point because ,in every article i read , the author mentions that c_s= 1/sqrt(3) without explanation.

Thank you very much.

Hi everybody,

I’m just looking for a clear answer or a reference that gives a demonstration on this point because ,in every article i read , the author mentions that c_s= 1/sqrt(3) without explanation.

Thank you very much.