I want to create an if loop inside multiple if loops that are already present

2 vues (au cours des 30 derniers jours)
I want to stop a piece of code once a certain variable goes past a certain number.
I am not sure exactly where to put it but essentially I want the code to stop once Vr is < arbitrary number, 0.004, let us say
if Vf_new < Vr(3,1) && delta_Vfc >= 1E-6
%
disp('update')
Vr(3,1) = Vf_new;
iter = iter + 1;
%
elseif delta_Vfc < 1E-6 || Vf_new <= Vr(3,1)
%
disp('do not update')
continue_iteration = 0;
%
end
It wants to appear here.
I am just not sure how to nest it inside an already existent if elif loop. I think it should look like this...
if Vf_new < 0.004
return
end
Help please
Thanks
Alex

Réponse acceptée

Image Analyst
Image Analyst le 30 Mar 2023
Not sure what you have: a for loop or multiple if/else blocks. An "if" block is not called a loop because it does not loop/iterate.
Let's say that you have a for loop and inside the for loop is your if tests and you want to check Vf_new at the beginning of the loop
for k = 1 : 10000
if Vf_new < 0.004
break; % Breaks out of the for loop and continues the program after the for loop.
% OR you can exit the loop and the entire function or program you're
% in by calling return;
% return; % Step out of the entire program.
elseif Vf_new < Vr(3,1) && delta_Vfc >= 1E-6
fprintf('Updating. Now Vf_new = %f.\n', Vf_new);
Vr(3,1) = Vf_new;
iter = iter + 1; % If iter is your for loop variable, then you don't need this line. If it's a while loop you may need this or something like it.
elseif delta_Vfc < 1E-6 || Vf_new <= Vr(3,1)
fprintf('NOT updating. Now Vf_new = %f.\n', Vf_new);
continue_iteration = 0; % If your loop is a for loop, then you don't need this line. If it's a while loop you may need this or something like it.
break; % Get out of loop. Do not continue iterating.
end
end
  1 commentaire
A Poyser
A Poyser le 30 Mar 2023
Modifié(e) : A Poyser le 30 Mar 2023
It is quite a long for loop so I only added what I thought was important for brevity, I will add a little more for context.
N = 1000;
%
% materials properties and preset variables goes here
%
for k = 1:N
%
k;
%
sigma_infty(:,k) = [10*k 0 0 0 0 0]'; % far-field stress
%
%
% Crack density parameter (from Budiansky and O'Connel, IJSS 12:81-97,
% 1976) in composite
cdp = 0.05; %
Vcc = 4/3*pi*cdp*a3_over_a1; % compute volumetric density of cracks in composite
%
if k == 1
Vr(3,1) = Vfc; % volume fraction of fibres
else
Vr(3,1) = Vfc*exp(-(sigma_f(1,k-1)/sYW)^mW); % volume fraction of the fibres corrected for failure based on the previous iteration
end
delta_Vfc = 1E6;
iter = 1;
continue_iteration = 1;
%
while continue_iteration && iter < 10
%
% some maths to calculate mechanical properties goes here...
%
Vf_new = Vfc*exp(-(sigma_f(1,k)/sYW)^mW);
delta_Vfc = abs(Vf_new-Vr(3,1));
%
if Vf_new < Vr(3,1) && delta_Vfc >= 1E-6
%
disp('update')
Vr(3,1) = Vf_new;
iter = iter + 1;
%
elseif delta_Vfc < 1E-6 || Vf_new <= Vr(3,1)
%
disp('do not update')
continue_iteration = 0;
%
end
%
end
end
%
I tried adding the piece of code that you suggested but it didn't seem to be able to break the loop.
Thanks
Alex

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