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

3 views (last 30 days)
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

Accepted Answer

Image Analyst
Image Analyst on 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 Comment
A Poyser
A Poyser on 30 Mar 2023
Edited: A Poyser on 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

Sign in to comment.

More Answers (0)

Categories

Find more on Loops and Conditional Statements in Help Center and File Exchange

Products


Release

R2022b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!