Error message with code

I am trying to write a code that plots TE waves for band structure showing allowed and forbidden bands. Below is what I have been able to come up with but it doesn't work! I am trying to tell matlab to plot a graph when the condition that m = or grater than + or -1 is met. In the work space when I run the code, m gives 1x300 which is definetely not correct! I want it to show 300X300.

Again, I get the error message "Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-2."

Your help would be highly appreciated.

clear all
n1=3.0;  %refractive index of medium 1
n2=2.2;  %refractive index of medium 2
a=0.5;    %thickness of medium 1 in microns
b=0.5;    %thickness of medium 2 in microns
c=300000000; %speed of light in vacuum;
Lambda= a+b; %period of the structure
M=300; N=M;
omega=linspace(1e-3,1,N); %angular frequency;
beta=linspace(1e-3,1,M);
m =[];
for j=1:N
    for k=1:M
    w=omega(k);
    B=beta(j);
B=(w./c); %propagation constant
b1=((w./c).*n1).^2;
k1=sqrt(b1-B.^2);
b2=((w./c).*n2).^2;   
k2=sqrt(b2-B.^2);
A(j,k)=exp(-1i.*k1.*a).*(cos(k2.*b)-(1i/2).*(k2./k1+k1./k2).*sin(k2.*b));
D(j,k)=exp(1i.*k1.*a).*(cos(k2.*b)+(1i/2).*(k2./k1+k1./k2).*sin(k2.*b));
m(j,k)=acos((A+D)./2); %m is a function of beta and omega
K=(1./Lambda).*m;  %K is a function of beta and omega
    end
end
[x,y]=meshgrid(omega,beta);
L=abs(m')>=1;
yte=y(L);
scatter(L,yte)

[VBBV]

Try this code below after some corrections. you will now get size of m as you wanted or specified 300x300. It does not show assignment or any errors now

clear all
n1=3.0;  %refractive index of medium 1
n2=2.2;  %refractive index of medium 2
a=0.5;    %thickness of medium 1 in microns
b=0.5;    %thickness of medium 2 in microns
c=300000000; %speed of light in vacuum;
Lambda= a+b; %period of the structure
M=300; N=M;
omega=linspace(1e-3,1,N); %angular frequency;
beta=linspace(1e-3,1,M);
m =[];
for j=1:N
    for k=1:M
    w=omega(j);
    B=beta(k);
B=(w/c); %propagation constant
b1=((w/c)*n1)^2;
k1=sqrt(b1-B^2);
b2=((w/c)*n2)^2;   
k2=sqrt(b2-B^2);
A(j,k)=exp(-1i*k1*a)*(cos(k2*b)-(1i/2)*(k2/k1+k1/k2)*sin(k2*b));
D(j,k)=exp(1i*k1*a)*(cos(k2*b)+(1i/2)*(k2/k1+k1/k2)*sin(k2*b));
m(j,k)=acos((A(j,k)+D(j,k))/2); %m is a function of beta and omega
K(j,k)=(1/Lambda)*m(j,k);  %K is a function of beta and omega
    end
end
% [x,y]=meshgrid(omega,beta);
% L=abs(m')>=1;
% yte=y(L);
% scatter(L,yte)

[Emma K.]

Thanks! Now it runs without errors but the graph is empty. What’s wrong? Could someone help out? Thank you

[Emma K.]

The graph I am trying to get is fig. 3 in “electromagnetic propagation in periodic stratified media.I General theory” by Pochi Yeh et al,1977. Thank you

[Sudhakar Shinde]

As you stated 'm' is a function of beta and omega. This 'm' variable now contains values less than or equal to 1 only and to plot on the values at last you used:

L=abs(m')>=1;

As there is no any values greater than 1 available in m variable, result is empty.