Trying to input values into function with previously symbolically defined variables and plot the function, but getting error

I wanted MATLAB to simplify T_h symbolically, and then wanted to graph T_h using the specific values of Ra, Rb, and Ca that you see below. For some reason, I keep getting the error "Conversion to double from sym is not possible." Any ideas? Thank you in advance!

clc; clear; close all;

syms w Rah Rbh Cah

%Simplifying High-Pass Gain Found

T_h = sqrt(((-Rah*Rbh.*(Cah.*w).^2)/((Rah.*w.*Cah).^2 +1)).^2 + ((-Rbh.*w.*Cah)/((Rah.*w.*Cah).^2+1)).^2);

pretty(T_h)

T_hs = simplify(T_h);

pretty(T_hs)

%Plotting High-Pass Gain vs Angular Frequency

w = 0:0.01:10000;

Rah_v = 10;

Rbh_v = 10;

Cah_v = 0.05;

T_hs_v = subs(T_hs,[Rah,Rbh,Cah],[Rah_v,Rbh_v,Cah_v])

figure

subplot(2,1,1)

semilogx(w,T_hs_v)

hold on

Answer 1

[Mischa Kim]

David, try

 ...
 %Plotting High-Pass Gain vs Angular Frequency
 ww     = logspace(1,5,100); 
 Rah_v  = 10;
 Rbh_v  = 10;
 Cah_v  = 0.05;

 T_hs_v = subs(T_hs,[Rah,Rbh,Cah],[Rah_v,Rbh_v,Cah_v]);
 T_hs_v = subs(T_hs_v,'w',ww);

 figure
 subplot(2,1,1)
 semilogx(ww,T_hs_v)
 hold on

I recommend defining a new variable ww that contains numeric values versus the symbolic variable w. Also, if you're planning to use a log plot it makes sense to assign values accordingly, e.g., using logspace.