Doug's MATLAB Video TutorialsDecember 3rd, 2010How to loop until a button is pushed in MATLABI had a question recently about having a process occur until a button is pressed in a GUI (or while a button is pressed). This video shows how a button can control the output of a stream of random numbers.
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This highlights one of the major limitations in Matlab. If you omit the pause in the callback you have a deadlock since the GUI would never refresh and you will not be able to stop the while-loop. If the callback, or should I call it the background task, is used to fetch data from an external source such as a web service or sensor then the GUI will remain unresponsive until the callback returns.
I’ve used timer as a poor mans substitute for threads and then simply used the callback to start and stop the timer. Still this solution is limited by matlabs single thread implementation.
Your tutorial inspired me to do this
http://www.mathworks.com/matlabcentral/fileexchange/29618
the code isn’t good but it works well and didn’t take much time to do.
Please keep posting great tutorials :)
@Trond
I believe a drawnow would work in the situation you are describing also. Both have the effect of calling for a clearing of the graphics queue.
@Paulo
Thanks for adding to the File Exchange.
Hi,
I have a problem with looping
here is my program, there’s no problem until defining A:
<if vbar(i)
all the steps give the expected answer which are 1*100 matrices.
but suddenly at the matrix part (A&B) I just get a 2*2 for A and a 2*1 for B meaning the loop only evaluates the 100th number of miu and other variables, but I have different values of miu(i)[1*100 matrix] ?! what is the problem here? or is it a problem?!
I dont know if the explanations are enough for you to understand the problem,
if needed I’ll describe more.
regards,
Sorry it seems that the program wasn’t sent
here it is:
%Initial Data rho=1.225; % Air density at 20 degrees Celcius(kg/m^3) R=7.5; % Main blade radius(m) N=4; % Number of blades W=7400; % Gross weight(Kg) omega=265*2*pi/60; % main blade rotation(rad/sec) Cl=5.73; % NACA 0012 lift-alpha coefficient(1/rad) Aeq=16*(0.3048^2); % Equivalent Area(m^2) v=linspace(0,73,100); % speed of Helicopter(m/sec) sig=N/(omega*R); % Solidity for i=1:100 Dfus(i)=rho*(v(i)^2)*Aeq/2; alphad(i)=Dfus(i)/W; T(i)=sqrt(W^2+Dfus(i)^2); CT(i)=T(i)/(rho*pi*(omega^2)*(R^4)); miu(i)=v(i)./(omega*R); % calculating labda using the graph of vbar_i vs. vbar vbar(i)=miu(i)./sqrt(CT(i)./2); if vbar(i)<=2 vbar_i(i)=sqrt(-(vbar(i)^2/2)+sqrt((vbar(i)^4/4)+1)); else vbar_i(i)=1/vbar(i); end % plot(vbar,vbar_i) % Matrices to solve theta0 and thetaC labda(i)=vbar_i(i)./(omega*R); A=[2/3+miu(i)^2 -miu(i);(8/3)*miu(i) -(1+((3/2)*(miu(i)^2)))]; B=[(4*CT(i))./(Cl*sig)+labda(i)+(miu(i)*alphad(i));2*miu(i)*(labda(i)+miu(i)*alphad(i))]; theta(:,i)=A\B; end theta0=theta(1,i); % Collective pitch thetaC=theta(2,i); % Cyclic pitch plot(v,theta0,'g') hold on plot(v,thetaC,'r')@Ali,
http://blogs.mathworks.com/pick/2007/08/20/matlab-basics-video/
I think this is what you are looking for.