For Loop nested within a while loop, run until condition is met
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My goal is to run an equation until my convergence criteria is met, basically do itterations until I am within some range of error. My code looks liek this
%% Model Cells
% Boundary conditions is head1 = 3 & head12=1
head = zeros (1,12); % Established a matrix of data
head(1)=3; % Setting boundary conditions
head(12)=1;
depth = [0.00,0.35,0.70,1.05,1.40,1.75,2.10,2.45,2.80,3.15,3.50,3.85];%for future plotting purposes
headold = zeros(1,12);
% Loop iteration & Stop iteration
x = ones(1,12);
cc = x*.001;
while headold-head<cc % solving for head until convergence criteria is met
headold = head;
% head = headold+1;
% headold+2 = headold+1;
for i=2:11
head(i)=(head(i-1)+head(i+1))/2; %solving for head 1 time
end
end
The result of this is a never ending matlab solution, however when I pause this I get the anser I want .
采纳的回答
darova
2020-2-19
This lines actually means: "loop if condition is met"
while headold-head<cc % solving for head until convergence criteria is met
Use this
tol = abs(head-headold);
while max(tol)>0.001 % solve if max(tolerance) > 0.001
%% ...
tol = abs(head-headold);
end
5 个评论
Nathan Pavlick
2020-2-20
Adam Danz
2020-2-20
Your while-loop is defined as while headold-head<cc. If you execute headold-head<cc you'll find that it produces a vector. The conditional expression should evaluate to a scalar logical value, not a vector. When the expression evaluates to a vector, all of the elements of the vector must be true for the while-loop to continue.
Here's a demo. Test the two x vectors.
x = logical([1 1 1 1 1]);
% x = logical([1 1 1 1 0]);
while x
disp('In while-loop')
x = false;
end
darova
2020-2-20
- Why though was mine not correct?
Because headold-head gives negative values only (cc is positive)
Try
while headold-head<cc % solving for head until convergence criteria is met
headold = head;
% head = headold+1;
% headold+2 = headold+1;
for i=2:11
head(i)=(head(i-1)+head(i+1))/2; %solving for head 1 time
end
plot(headold-head)
pause(0.1)
end
Adam Danz
2020-2-20
@dovara, but headold-head<cc will still produce a vector which is the problem I mentioned above.
darova
2020-2-20
You are right
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