plot the graph of function

l=633;

k0=2*pi/l;

ea=1.39;

da=1:300;

theta=1:70;

y=zeros(length(theta),length(da));

np=1.5;

x=(2*pi/l)*np*sind(theta);

for i=1:length(theta)

for j=1:length(da)

ka=k0*sqrt(ea-x.^2);

f=(1-exp(2*1i.*da(j).*ka(i)))/(1+exp(2*1i.*da(j).*ka(i)));

%pfms=2*atan(1i*a.*b);

y(i,j)=2*atan(1i*c.*f);

disp(y)

end

end

plot(da,y )

error message pl plot between da vs y and dy/da vs da

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-100.

[Walter Roberson]

c is not defined in the code

[shiv gaur]

c is =1

[shiv gaur]

how to plot dy/dda vs da

Answer 1

[Kevin Hanekom]

clc;clear;close all;

l=633;
c = 1;

   
k0=2*pi/l;
ea=1.39;
da=1:300;
theta=1:70;
y=zeros(length(theta),length(da));
np=1.5;
x=(2*pi/l)*np*sind(theta);

for i=1:length(theta)
    iter = 0;
    for j=1:length(da)
        iter
ka=k0*sqrt(ea-x.^2);
f=(1-exp(2*1i.*da(j).*ka(i)))/(1+exp(2*1i.*da(j).*ka(i)));
%pfms=2*atan(1i*a.*b);
y(i,j)=2*atan(1i*c.*f);
   
%  disp(y);
    
 iter = iter + 1;
    end
end
    
 plot(da,y )  
 

What exactly is wrong?

[shiv gaur]

this program is working pl help one pl plot da vs dy/dda

why this is not working in function define

clc;clear;close all;

l=633;
c = 1;


k0=2*pi/l;
ea=1.39;
da=1:300;
theta=1:70;
y=zeros(length(theta),length(da));
np=1.5;
x=(2*pi/l)*np*sind(theta);
function y=f(theta,da)

for i=1:length(theta)
    iter = 0;
    for j=1:length(da)
        iter
        ka=k0*sqrt(ea-x.^2);
        f=(1-exp(2*1i.*da(j).*ka(i)))/(1+exp(2*1i.*da(j).*ka(i)));
        %pfms=2*atan(1i*a.*b);
        y(i,j)=2*atan(1i*c.*f);
        
        %  disp(y);
        
        iter = iter + 1;
        plot(da,y ) 
    end
end

end  

your program in not working pl help

[Walter Roberson]

@shiv gaur

That code never calls the function f

Reminder: your y is a 2D array that is changing in size as you go (since you do not pre-allocate). And each time you assign to a new y(i,j) location, you are plotting using the constant-sized vector da as the independent variable, and using all of the changing-size y as the dependent variable. That is going to run into size mismatches, and is also going to be attempting to plot locations in y that have not been explicitly given a value yet.

What is the point of doing the plot inside the double nested loop?

It might make sense to plot at the end of the double nested loop.

... but it would probably make more sense to return y to the calling function and let the calling function plot whatever it wants.