where do i make mistake in my loop

dear friends, i am facing problem in my for loop to draw the itertaion number versus w.

w has an effect to the iteration number of this problem, when Wopt is 1.78 and the iteration number is 63.

i am checking the number for w from 0 up to 2. for an example, i am sharing the iteration versus graph below my code.

thanks for your support.

clear
close all, clc
format short

%Defining the constants
L=5;                                % length
H=5;                                % Height
deltax=0.2
deltay=0.2
Beta=deltax/deltay
Beta2=Beta^2
jn=H/deltay                         % Maximum number of grid points along y
im=L/deltax                         % Maximum number of grid points along x
Si1=100; Si2=0;                     % boundary conditions

y=H:-deltay:0;
x=0:deltax:L;

a= round(((cos(pi/im)+cos(pi/jn))/2)^2,4)
Wopt= round(( (2-2*(sqrt(1-a)))/a ),2)          % Relaxation Method
w=0:0.01:2;                                        % to draw iteration graph

% initialize T_old to the initial guess values
Si_old=zeros(jn+1,im+1);
% set boundary conditions
Si_old(1,7:im+1)=Si1;           % 5 ft TOP
Si_old(jn+1,1:im+1)=Si2;        % 3 ft bottom
Si_old(1,6)=0.001;            % inlet

Si_old(1:jn+1,1)=Si2;           % 5 ft left side 
Si_old(1:16,im+1)=Si1;       % 3.8 ft right side
Si_old(17,im+1)=0.001;            % outlet
Si_new = Si_old;
Error = 0.011;  % could be any number that is greater than Errormax
Errormax=0.01;

iter=0;

for o=1:length(w)   %the loop for iteration graph

while Error > Errormax
    iter(o)=iter+1;

for i=2:jn 
for j=2:im
    Si_new(i,j)=(1-w(o))*Si_new(i,j) + (w(o)/(2*(1+Beta2)))* (Si_new(i-1,j)+Si_new(i+1,j)+Beta2*(Si_new(i,j+1)+Si_new(i,j-1)) ) ;       
end
end
Error = sum(sum(abs(Si_old-Si_new),2))   ; 
Si_old = Si_new;

end
    if o==Wopt
        Si_new=flip(Si_new);
        disp(' ');disp('        Y        x=0.0   X=1.0     X=2.0     X=3.0     X=4.0     X=5.0      ')
        disp(' ');
        disp([y' Si_new(:,find(abs(x-0.0) < 0.001)) Si_new(:,find(abs(x-1) < 0.001))...
            Si_new(:,find(abs(x-2) < 0.001)) Si_new(:,find(abs(x-3) < 0.001))...
            Si_new(:,find(abs(x-4) < 0.001)) Si_new(:,find(abs(x-5.0) < 0.001))])
        disp(' '); disp(['Number of iteration for Point Successive Over Relaxation method is ',int2str(iter)])
    end
    
figure(2)
plot(t(o),w(o)); hold on

end

[Walter Roberson]

Wopt= round(( (2-2*(sqrt(1-a)))/a ),2)          % Relaxation Method

so Wopt is rounded to two decimal places

for o=1:length(w)   %the loop for iteration graph

o will be an integer

     if o==Wopt

are you sure you want to compare your two-decimal-place Wopt to the integer o ??

[mehmet salihi]

i had to put all matrix initialization inside the first loop. and some modification as you wrote have been done

thank you for help.

Answer 1

[Houssem]

First t is not defined in the program, second w is not calculated in your program

[Walter Roberson]

w=0:0.01:2;

is in the code.

[mehmet salihi]

i had to put all matrix initialization inside the first loop.

thank you for help.