Array indices must be positive integers or logical values.

Hello everyone,

I'm a bit rusty with Matlab since I didn't use it for a long time, but I struggle with a simple problem.

The problem is that I extracted this code from a book so I really expected it to work... It is about cell properties modelling.

When I run the code below I get the following error :

Array indices must be positive integers or logical values.

Error in test (line 39)

keff2 = k2 .*(am2(k1+2*k2)-2*am1*(k2-k1))./(am2*(k1+2*k2)-am1*(k1-k2));

Could anyone help me to figure it out ? I shoul have an array of values depending on the frequency but the code won't run.

Thanks a lot !

W.

% CMfactor.m
% the particle is assigned a conductivity kc1 and permittivity kp1.
% the suspending medium has conductivity kc2 and permittivity kp2.
% ki (i=1, 2) complex permittivity of particle, amd medium
% p0: permittivity of free space
% All parameters in SI Units (metres, S/m, F/m).
% 

p0=8.854e-12;
% Membrane thickness d, cell raidus a2
d=7e-9;
a2=5e-6;
a1=a2-d;


f=logspace(3,9,120);
zeroline=f-f;
w=2*pi*f;

% Cytoplasme
kc1=0.8;
kp1=50*p0;
% Membrane
G=0.2;
kc2=G*d
C=8e-3;
kp2=C*d;


% kc1=10e-3;
% kp1=10*p0;
% kc2=10e-4;
% kp2=80*p0;

k1=kp1-i*kc1 ./w;
k2=kp2-i*kc2 ./w;

am1=a1^3;
am2=a2^3;
keff2 = k2 .*(am2(k1+2*k2)-2*am1*(k2-k1))./(am2*(k1+2*k2)-am1*(k1-k2));

rm = real(keff2)

plot(log10(f), rm, '-', log10(f),zeroline, '-');
text(6.2, 0.3,'Re'), text(5.2, -0.3, 'Im')
xlabel('Log Frequency (Hz)')
ylabel('Relative permittivity')
hold on;

Answer 1

[KALYAN ACHARJYA]

keff2 = k2 .*(am2*(k1+2*k2)-2*am1*(k2-k1))./(am2*(k1+2*k2)-am1*(k1-k2));

More:

p0=8.854e-12;
% Membrane thickness d, cell raidus a2
d=7e-9;
a2=5e-6;
a1=a2-d;
f=logspace(3,9,120);
zeroline=f-f;
w=2*pi*f;
% Cytoplasme
kc1=0.8;
kp1=50*p0;
% Membrane
G=0.2;
kc2=G*d
C=8e-3;
kp2=C*d;
% kc1=10e-3;
% kp1=10*p0;
% kc2=10e-4;
% kp2=80*p0;
k1=kp1-i*kc1 ./w;
k2=kp2-i*kc2 ./w;
am1=a1^3;
am2=a2^3;
keff2 = k2 .*(am2*(k1+2*k2)-2*am1*(k2-k1))./(am2*(k1+2*k2)-am1*(k1-k2));
cmf=(k1-k2) ./(k1+2*k2);
rm=real(cmf);
im=imag(cmf);
rm = real(keff2)
plot(log10(f), rm, '-', log10(f), im, '-', log10(f),zeroline, '-');
text(6.2, 0.3,'Re'), text(5.2, -0.3, 'Im')
xlabel('Log Frequency (Hz)')
ylabel('Relative permittivity')

[Will]

Sorry I just edited my code there were some leftovers of my previous modifications tries.

The correct version is now updated.

[KALYAN ACHARJYA]

% CMfactor.m
% the particle is assigned a conductivity kc1 and permittivity kp1.
% the suspending medium has conductivity kc2 and permittivity kp2.
% ki (i=1, 2) complex permittivity of particle, amd medium
% p0: permittivity of free space
% All parameters in SI Units (metres, S/m, F/m).
% 
p0=8.854e-12;
% Membrane thickness d, cell raidus a2
d=7e-9;
a2=5e-6;
a1=a2-d;
f=logspace(3,9,120);
zeroline=f-f;
w=2*pi*f;
% Cytoplasme
kc1=0.8;
kp1=50*p0;
% Membrane
G=0.2;
kc2=G*d
C=8e-3;
kp2=C*d;
% kc1=10e-3;
% kp1=10*p0;
% kc2=10e-4;
% kp2=80*p0;
k1=kp1-i*kc1 ./w;
k2=kp2-i*kc2 ./w;
am1=a1^3;
am2=a2^3;
keff2 = k2 .*(am2*(k1+2*k2)-2*am1*(k2-k1))./(am2*(k1+2*k2)-am1*(k1-k2));
rm = real(keff2)
plot(log10(f), rm, '-', log10(f),zeroline, '-');
text(6.2, 0.3,'Re'), text(5.2, -0.3, 'Im')
xlabel('Log Frequency (Hz)')
ylabel('Relative permittivity')
hold on;

[Will]

Oh I see I did a typo in the formula ... Thanks for pointing it out !