While loop doesn't stop

Hey I've created the code described beneath but it doesn't run as planned. When I run it, the inner while loop 'while zonestop == 0' doesn't stop when it's condition isn't met anylonger? I can see that the condition is met in the command window.

Any help would be appreciated :)

%Debugging

clear clc %restarter alle kommandoer i Command window %alt køres ind med mm, N og MPa

% trinproces er 0,70 mm og stempeldiameteren er 110 mm

r = zeros(70,4); %preallocating = skrives for at lave hele matricen fra start, så det går hurtigere t = zeros(70,4); %; skrives for at matricen ikke skrives ud epsilontheta = zeros(70,4); epsilonn = zeros(70,4); epsilonr = zeros(70,4); den = zeros(70,4); det = zeros(70,4); der = zeros(70,4); epsilons = zeros(70,4); sigmas = zeros(70,4); sigman = 2*ones(70,4);%den første betingelse gør at sigman ikke må være 0 indledningsvis sigmar = zeros(70,4); k = zeros(70,4); l = zeros(70,4); A = zeros(70,1); F = zeros(29,1);

for i = 1:70 r0=110;%mm t0=1; %mm R=1.70; K=530; %N/mm^2 = MPa n=0.268; my=0.2;

    for j =1:4
        r(1,j)=r0-0.5*(j-1);
        r(i,1)=r0-1*(i-1);
    end

    %j = 1
    t(1,1)=t0;
    t(i,1)=t(1,1); 

    epsilonn(i,1)=0;
    epsilontheta(i,1)=0;
    epsilonr(i,1)=0;

    epsilons(i,1)=0;
    sigmas(i,1)=0;

    k(i,1)=0;
    l(i,1)=0;

    sigmar(i,1)=0;
    sigman(i,1)=0;
    F(i,1)=0;
end

    j=2;
    i = 1;
    done = 0;
    dt = 0;
    zonestop = 0;

while j <= 4

    while done == 0 %når denne løkke er færdig j=j+1        

        while zonestop == 0        
            if j ~= 1
                t(i,j)=t(i,j-1)+dt; %startantagelse af tykkelsen, dt ændrer sig            
                if i ~=70 %tykkelsen i hvert procestrin er ens
                    t(i+1,j)=t(i,j-1)+dt;

                    tic; r(i+1,j)=sqrt((2*((r(i,j))^2*(t(i,j)+t(i+1,j))/(2)-((r(i,1))^2-(r(i+1,1))^2)*t(i,1)))/(t(i,j)+t(i+1,j))); toc;
                end                        
            tic; epsilonn(i,j)=log(t(i,j)/t0); toc; 
            tic; epsilontheta(i,j)=log(r(i,j)/r(i,1)); toc;
            tic; epsilonr(i,j)= -(epsilonn(i,j) + epsilontheta(i,j)); toc;

            tic; den(i,j)=epsilonn(i,j) - epsilonn(i,j-1); toc;
            tic; det(i,j)=epsilontheta(i,j) - epsilontheta(i,j-1); toc;
            tic; der(i,j)=-(den(i,j)+det(i,j)); toc;

            tic; epsilons(i,j)=(sqrt(R+1))^2/(R+1)*sqrt(R*(der(i,j)-det(i,j))^2+(der(i,j)-R*den(i,j))^2+(det(i,j)-R*den(i,j))^2); toc;
            tic; sigmas(i,j)= K*(epsilons(i,j))^n;toc;

            tic; k(i,j)= sigmas(i,j)/epsilons(i,j)*((1+R)/(1+2*R))*(2*det(i,j)+den(i,j)); toc;
            %k=(sigmatheta(i,j)-sigmar(i,j))
            tic; l(i,j)= sigmas(i,j)/epsilons(i,j)*((1+R)/(1+2*R))*(den(i,j)*(1+R)+det(i,j)); toc; %den(i,j) = 0
            %l=(sigman(i,j)-sigmar(i,j))

                sigmar(1,j) = 0;           
                if i ~= 70 %for sigmar = 2:70
                    if j~=1 %er allerede defineret
                    tic; sigmar(i+1,j)=(sigmar(i,j)+(0.5*((k(i+1,j))/(r(i+1,j))+(30*k(i,j))/(r(i,j)))+(my)/(t(i,j))*((l(i+1,j))+sigman(i,j)))*(r(i+1,j)-r(i,j)))/(1-(my)/(t(i,j))*(r(i+1,j)-r(i,j))); toc;    
                    end
                end
            end

            if j == 1 % der er et loop inden i loopet
                sigman(i,1) = 0;
            else
                if i==1                    
                tic; sigman(1,j)= l(1,j); toc; %ved i=1 er sigmar = 0 
                else
                tic; sigman(i,j)=l(i,j)+sigmar(i,j); toc;
                end
            end

            if sigman >= 0
                zonestop = 1;
            else
                i = i+1;
                zonestop = 0;
            end
        end %while zonestop == 0
           i
        Fanvendt = 2.8*10^4; %N
        if i ~= 70 %50 radier, men 49 ringelementer
            F(i,1)= sigman(i,j)*((r(i,j))^2-(r(i+1,j))^2)*pi;
        end

        if sqrt((sum(F))^2)-Fanvendt > 0.01*Fanvendt %istedet for numerisk tegn
            dt = dt + 0.01;
            done = 0;
        else           
            done = 1;
        end
    end
    j=j+1;
end
t

[Jan]

Please use a proper code formatting as explained in the "Markup help" link on this page.

It would be smarter, if you post only the part of the code, which reproduces the problem.

Especially "tic; ...; toc;" is 1. a waste of computing time, because it doesn't display the results, and 2. a waste of the time of all readers of your question.

Answer 1

[David Young]

The stopping test boils down to

if sigman >= 0

This only counts as true if all elements of the matrix sigman are greater than or equal to zero. If sigman has a negative element anywhere, the loop will continue. Is that what you want, or did you maybe mean

if sigman(i,j) >= 0

Answer 2

[Jan]

It is not helpful to include all lines in tic and toc. You cannot get a reliable time measurement by this method. Remember, that the JIT acclereation requires, that each line contains a single command only.

This test:

if sigman >= 0

is equivalent to:

if all(sigman >= 0)

if sigman is not a scalar. Is this the wanted behaviour? If not, it does not trigger the setting of zonestop = 1; and this would lead to your problem.