Function 'quadprogIP' runs fast seperately but extremely slow in a for loop simulation

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I am currently using the function 'quadprogIP' from
This is a function that solves a nonconvex quadratic optimization, via IBM Cplex function for mixed-integer linear programming. My problem is: if I run the function 'quadprogIP' once, it executes very fast (around 10 minute).
n = 50;
f = zeros([n,1]);
A = zeros(n); b = zeros([n,1]);
Aeq = ones([1,n]); beq = 1;
LB = zeros([n,1]); UB = ones([n,1]);
epsilon = 1e-6;
sigma = 2*rand(1,n);
rho = rand(n);
Cov = sigma.'*sigma.*rho;
rhoc = ones(n);
Covc = sigma.'*sigma.*rhoc;
low = 0; high = 1; iter = 1;
q = (low+high)/2; H = Cov-q*Covc;
[w,Fq,time,stats] = quadprogIP(H,f,A,b,Aeq,beq,LB,UB,[]);
TT(iter) = stats.total_time % This is normally 10 seconds
But if I wanna run a while loop, and the function 'quadprogIP' is called upon in the loop, the average time for each execution is much longer (at least 5 times higher).
while abs(Fq) > epsilon
if Fq>0
low = q;
high = q;
iter = iter+1;
q = (low+high)/2;
H = Cov-q*Covc;
[w,Fq,time,stats] = quadprogIP(H,f,A,b,Aeq,beq,LB,UB,[]); % from Github
TT(iter) = stats.total_time
mean(TT) % But this one is a lot higher.
I don't know what could be the possible reason for this situation, and if there is any way to solve this problem. Thanks!

Answers (1)

Torsten on 14 Sep 2023
Moved: Torsten on 14 Sep 2023
Maybe the problems to be solved get larger or more complicated within the for loop so that the average time spent for each problem increases ? But we can only speculate without your code.
Since "quadprogIP" is not an official MATLAB tool, I'd suggest to contact the authors.
  1 Comment
Churui Li
Churui Li on 14 Sep 2023
Thank you for answering! I added the relevant code in the post.
Indeed it is not an official Matlab function, I may turn to the authors if the problem remains after a while.

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