How to tell matlab that y is a function of x; not a constant

I have a function z such that z=xy(x) , [i.e. y is a function of x]. So if I differentiate z with respect to x, I shoud get dz/dx= y+x*(dy/dx). However if I use diff(z,x) in matlab, I get only y [matlab treats y as a constant]. What should I do to define y as a function of x?

syms x y z
z=x*y;
diff(z,x)
 
ans =
 
y

Answer 1

[Star Strider]

In the initial syms call, declare ‘y(x)’ instead of ‘y’ —

syms x y(x) z
z=x*y;
Dz = diff(z,x)                                              % Create Assignment

Dz(x) = 

Note that now ‘Dz’ is also a funciton of ‘x’, as it should be.

[Ayan PATSA]

Thank you..It works.

[Star Strider]

As always, my pleasure!