I cant get the correct plotting

I am trying to acheive a specfic graph but the code is not giving me the correct respond needed. The equations are correct but not giving the specfic values needed. I assume its an issue with the loop.

% Given
p = 7500; % kg/m^3
Cd33 = 16*10^10; %N/m^2
vp= 4620; % Ns/m
Ceb = 1.43E-9; % F
phi = 2.62; % As/m

% Piezoelectric Disk Material
dia = 12e-3;
radius = dia/2;
A = pi*radius^2;
tp = 1e-3;

% Water properies for mathcing layer
pw = 1000; 
cw = 1500;
vm = 3000;
f0 = vp/4*tp;
tm = vm/4*f0;

% Frequency range
f = linspace(100e3, 2.2e6,200);

alpha = 1;

% Impedence 
Rrad = pw*cw*A;
Z0p = 3920; % Ns/m


% frequency range
v0e = zeros(length(f),length(alpha));
% Loop Start
for i = 1:length(alpha)
    for j = 1:length(f)
        w = 2*pi*f(j);
        km = w/vm;
        kp = w/vp;
        Z0m = alpha*Rrad;
        Zcem = phi^2/1j*w*Ceb;
        Zm1 = 1j*Z0m*tan(km*tm/2);
        Zm2 = Z0m/(1j*sin(km*tm));
        Zp1 = 1j*Z0p*tan(kp*tp/2);
        Zp2 = Z0p/(1j*sin(kp*tp));
        Z = [Zm1+Zm2+Rrad, -Zm2,     0;
        -Zm2, Zp1+Zp2+Zm1+Zm2, -Zcem;
        0,    -Zcem,          Zcem];
        v0e(j) = phi*[1 0 0]*Z^-1*[0;0;1];
    end
    v0e(:,i) = v0e(j);
end

figure(1)
semilogy(f, abs(v0e),'linewidth', 2)
xlabel('Frequency [Hz]', 'fontsize', 15)
ylabel('Magnitude [Ns/m]', 'fontsize', 15)
grid on
figure(2)
plot(f, (180/pi)*v0e ,'linewidth', 2)
xlabel('Frequency [Hz]', 'fontsize', 15)
ylabel('phase [deg]', 'fontsize', 15)
grid on 

Answer 1

[Torsten]

% Given
p = 7500; % kg/m^3
Cd33 = 16*10^10; %N/m^2
vp= 4620; % Ns/m
Ceb = 1.43E-9; % F
phi = 2.62; % As/m

% Piezoelectric Disk Material
dia = 12e-3;
radius = dia/2;
A = pi*radius^2;
tp = 1e-3;

% Water properies for mathcing layer
pw = 1000; 
cw = 1500;
vm = 3000;
f0 = vp/4*tp;
tm = vm/4*f0;

% Frequency range
f = linspace(100e3, 2.2e6,200);

alpha = 1;

% Impedence 
Rrad = pw*cw*A;
Z0p = 3920; % Ns/m


% frequency range
v0e = zeros(length(f),length(alpha));
% Loop Start
for i = 1:length(alpha)
    for j = 1:length(f)
        w = 2*pi*f(j);
        km = w/vm;
        kp = w/vp;
        Z0m = alpha(i)*Rrad;
        Zcem = phi^2/1j*w*Ceb;
        Zm1 = 1j*Z0m*tan(km*tm/2);
        Zm2 = Z0m/(1j*sin(km*tm));
        Zp1 = 1j*Z0p*tan(kp*tp/2);
        Zp2 = Z0p/(1j*sin(kp*tp));
        Z = [Zm1+Zm2+Rrad, -Zm2,     0;
        -Zm2, Zp1+Zp2+Zm1+Zm2, -Zcem;
        0,    -Zcem,          Zcem];
        v0e(j,i) = phi*[1 0 0]*Z^-1*[0;0;1];
    end
end

figure(1)
semilogy(f, abs(v0e),'linewidth', 2)
xlabel('Frequency [Hz]', 'fontsize', 15)
ylabel('Magnitude [Ns/m]', 'fontsize', 15)
grid on

figure(2)
plot(f, (180/pi)*v0e ,'linewidth', 2)

Warning: Imaginary parts of complex X and/or Y arguments ignored.

xlabel('Frequency [Hz]', 'fontsize', 15)
ylabel('phase [deg]', 'fontsize', 15)
grid on 

[Abdullah Alsayegh]

How to fix the error " Warning: Imaginary parts of complex X and/or Y arguments ignored."

[Torsten]

I guess voe is complex-valued. And MATLAB does not like to plot complex values against real values. Thus it only plots the real part of 180/pi*voe against f.