You have
z(r,phi)=J*((3.8316*r)*cos(rho))
This is not valid. r on the left side is a vector of floating point numbers, but those are not valid indices. You have not defined phi. If we assume that this should be a symbolic function definition, that you previously did a "syms phi", then you have the problem that you defined r numerically and you cannot use numeric variables when defining a symbolic function.
I suspect you want
syms R RHO
z(R, RHO) = J*((3.8316*R)*cos(RHO))
or
z = @(r, rho) J*((3.8316*r)*cos(rho))
On the other hand if you review back to the question you will find that J subscript 1 is the notation used for the Bessel function of the first kind. This is a function call, not a constant to be multiplied.
syms x
J1(x) = besselj(1,x)
or
J1 = @(x) besselj(1,x)
