how to create symbolic function?

I need to transform the following function to the symbolic form to evaluate it with arbitrary precision.

Z(N,Thetas) = prod((1 - exp(-(N:-1:2).*Thetas))./(1 - exp(-Thetas)),2)

where Thetas is matrix M x N-1 of the positive real numbers. So the expected result is vector Z (M x 1). I am not able to rewrite function Z to symbolic form and than evaluated it by vpa() command.

Any idea how to effectively solve it?

Answer 1

[Michal]

function Z=symZ(N,Thetas,Ndigit)
Thetas = sym(Thetas);
Zsym = prod((1 - exp(-(N:-1:2).*Thetas))./(1 - exp(-Thetas)),2);
Z = vpa(Zsym,Ndigit);
end

Answer 2

[Alfonso Salas-Cruz]

how evaluate an symbolic expresion?

[Michal]

use the "vpa" command:

Z = vpa(Zsym,Ndigit);