Index exceeds the number of array elements (2).

clear all; clc;

format long
 
en=10^-50;
q=0.9;
o=0.5;
xi=1;
U=1;
gema=i/(6*i+1);

xn(:,1)=-2;
xn(:,2)=1;
i=2; 
tic;
while (norm( xn(:,i)- xn(:,i-1) ) > en)
theta(2)= ((q*i)/(i+3)); 
Thta(2)=((o*i)/(i+3));
s=0.017;
gema=i/(6*i+1);
    r(i)=1/(100*i+1);  %is used for r(n) 
    yn(:,i)= (xn(:,i)+theta(i)*(xn(:,i)-xn(:,i-1)));
    y1n(:,i)=(xn(:,i)+Thta(i)*(xn(:,i)-xn(:,i-1)));
     cn(:,i)=(yn(:,i)-3*s*U*y1n(:,i));
     Sn(:,i)=xn(:,i)+xi*((((1-3*s*U)/(1+s*U*4))*cn(:,i)-xn(:,i)));  
     xn(:,i+1)= Sn(:,i);
    
    if (xn(:,i) ~= xn(:,i-1))
        theta(i+1)= min( 1 /( (i+1)^2 *norm( xn(:,i) - xn(:,i-1) ) ), 0.5 ); % theta reprsents theta
    else
        theta(i+1)= 0.5;
    end
theta(i+1)
     i=i+1

end

Out Put:

Index exceeds the number of array elements (2).

Error in theeta_fileVMFB (line 27)

y1n(:,i)=(xn(:,i)+Thta(i)*(xn(:,i)-xn(:,i-1)));

Answer 1

[Voss]

This error happens the second time through the while loop (that is, i == 3). The cause of the error is that Thta only has 2 elements, but this line is trying to reference Thta(3).

[Walter Roberson]

Right. You extend theta as you go but you do not extend Thta as you go.

[YASIR ARFAT]

its again give error like that: when i put the value i=3; then it gives this error. so how can i reduce this error and then it will run properly so please guide me, thanks for your kind cooperation.

Index in position 2 exceeds array bounds (must not exceed 2).

Error in theeta_fileVMFB (line 19)

while (norm( xn(:,i)- xn(:,i-1) ) > en)

[Voss]

When you say you "put the value i=3," do you mean you set i to be 3 before the while loop? If so, then that explains the error in line 19. xn has size 2 in dimension 2, so referencing xn(:,3) is out of bounds and will generate that error.

[YASIR ARFAT]

yes you are right but i need your help please run this program or tell me how to reduce this error and then it is ready for output so please solve this problems or tell me in above mention matlab code before what i do then this error will remove. Thankyou.

[Voss]

There are many ways to avoid running into this error, but just having the code run without errors doesn't mean the code is correct or the results are right. Like Walter Roberson observed, the variable theta grows by one element each time through the while loop, but Thta does not. Perhaps correcting this inconsistency in an appropriate manner would be all you need to do. (But I cannot say what is appropriate and whether this would be sufficient because I don't know what theta and Thta represent and I don't know what the code is supposed to be doing.)