MATLAB Solve equtaion with sinh en coth in matlab

[mrcannibal]

Hi, I need the numerical solution of C. But i get an Error: argument must be of 'Type::Arithmetical' [sinh]! Can you help me the code please,I would be of great help!
Thanks

syms x

Bi = 0.43;

t = -16.9;

N = x/(2*Bi)+ t/2;

y = 2*(1-coth(x))*(cosh(x)-cosh(N))+x/((2*Bi)*exp(-N))+(1-coth(x)/(2*Bi))*x*sinh(x);

P = solve(y);

M = P/(2*Bi)+t/2;

C = (P^2/sinh(P)^2)*exp(-M)*(cosh(P)-cosh(M));

 

[n.karthick]

Hi, declare Bi and t also as syms variables, it worked for me