How to append in a while loop?

Hello,

I am trying to run a loop to get the values of lambda in an array, number of rows is unknown, which to be determined when a certian limit is met. For each n there supposed to be 2 values each for W ,c ,lambda ,phi

The goal is to keep lambda values and ph values as they will be used in other steps. I was trying to append

When all added at the end it should be like,

when n =1 , we get:

lambda 1

lambda 2

n=2,

lambda 3

lambda 4

.

.

and so on.

The code I wrote seem to have some issue with the indices, I am fairly new to matlab so I am not sure how to the fix should be. Any help is appreciated.

limit =0.01; 
repeat= true; 
Ad= (linspace(-2.5,2.5,26))';
b=2; 
n=1;

while repeat==true
    
    syms z
    W(n)= vpasolve(1/b -z*tan(z*a), z, [(n-1)*(pi/a)  (n-(1/2))*(pi/a)]);
    c(n)= 1/((a+(sin(W(n)*a)/2*W(n)))^0.5);
    lambda(n)= (2*b)/(1+((W(n)^2)*(b^2)));
    ph(n)= c(n)*cos(W(n)*Ad(n));
    
    
    W(n)= vpasolve(((1/b *tan(z*a)) + z), z, [(n-(1/2))*(pi/a)  (n)*(pi/a)]);
    c(n)= 1/((a-(sin(W(n)*a)/2*W(n)))^0.5);
    lambda=[(2*b)/(1+((W(n)^2)*(b^2))),n];
    ph= [c(n)*sin(W(n)*Ad(n)),n];
    
    if lambda(n)/lambda(1) < 0.01
        repeat= false;
    end
    n=n+1;
end

I get an error for the if line ,

Index exceeds the number of array elements (2).

Answer 1

[David Hill]

Where is 'a' assigned? Lots of guessing here, but this might help you.

limit =0.01; 
Ad= (linspace(-2.5,2.5,26))';
b=2;a=1;
n=1;
while 1
    
    syms z
    W(n,1)= double(vpasolve(1/b -z*tan(z*a), z, [(n-1)*(pi/a)  (n-(1/2))*(pi/a)]));
    c(n,1)= 1/((a+(sin(W(n,1)*a)/2*W(n,1)))^0.5);
    lambda(n,1)= (2*b)/(1+((W(n,1)^2)*(b^2)));
    ph(n,1)= c(n,1)*cos(W(n,1)*Ad(n));
    
    
    W(n,2)= double(vpasolve(((1/b *tan(z*a)) + z), z, [(n-(1/2))*(pi/a)  (n)*(pi/a)]));
    c(n,2)= 1/((a-(sin(W(n,2)*a)/2*W(n,2)))^0.5);
    lambda(n,2)=(2*b)/(1+((W(n,2)^2)*(b^2)));
    ph(n,2)= c(n,2)*sin(W(n,2)*Ad(n));
    
    if lambda(n,1)/lambda(1,1) < 0.01
        break;
    end
    n=n+1;
end

[Maram]

Sorry I forgot to mention, a=2.5

It's extremely helpful tho, thank you so much for your quick reply!