How to make an anonymous function whose variable is itself a function of another variable?

Let's say i have an anonymous function defined in the following manner

z = @(x) cos(phi).^2 + 4*sin(phi).^2 and phi is defined in the following way

phi = @(x) x.^3 + 4*x.^2 + x +3

I have been trying to do this but when i call the function z in the following way, an error pops up

z(3)

Is something wrong in the syntax?

Answer 1

[George Papazafeiropoulos]

z = @(phi) cos(phi).^2 + 4*sin(phi).^2

phi = @(x) x.^3 + 4*x.^2 + x +3

z(phi(3))