How to fix equation code error

I would like to know if I'm coding this equation correctly?? I'm getting a error. Any help will be appreciated. Thanks.

nu = 1.5e-5; 
ya = 9.7;
k = 0.41;
y = 2.3025e-03;

uT = (k.*rho.*nu).*((y.*ustar/nu) - ya.*tanh((y.*ustar/nu)/ya))

[Dyuman Joshi]

From equation standpoint, the formula is correct. Apart from what Steven has mentioned below, are you facing any other problem?

[Torsten]

We are full of expectation to see the error message and the values of rho and ustar to evaluate the expression for uT.

Answer 1

[Steven Lord]

nu = 1.5e-5; 
ya = 9.7;
k = 0.41;
y = 2.3025e-03;

uT = (k.*rho.*nu).*((y.*ustar/nu) - ya.*tanh(y.*ustar/nu.*ya))

Unrecognized function or variable 'rho'.

Nowhere in this code do you define the variables rho or ustar.