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Asked by Lawson Hoover on 8 Dec 2012

I am trying to animate a plot. I have got it to work but I seems to moving a tad slow, and Also when I allocate the frames into a variable M with getframe, the M gets a red underline saying that I should preallocate for speed. I have been trying to do this but I get is the error:

The following error occurred converting from struct to double: Error using double Conversion to double from struct is not possible.

I have no idea how to fix this. The code I am using is below:

plot(x,y,'--r','LineWidth',3); % original position xlabel('Beam Length (in.)','Color','g'); ylabel(bstr,'Color','g'); ylim([-(Beam.y(10)) max(Beam.y)]); title(astr,'Color','y','fontweight','b'); set(S.ax,'YDir','reverse'); set(S.ax,'XGrid','on'); set(S.ax,'YGrid','on'); y =0; z = 0; hold on clear M M = zeros(1,100); ht = plot(y,z,'-b','linewidth',2); % new position for i = 1:100 if i == 1 set(ht ,'XDataSource','Beam.x') set(ht,'YDataSource','Beam.y') end set(ht,'XData',Beam.x(1:i)) set(ht,'YData',Beam.y(1:i)) M(i) = getframe(gcf); % this says that I shoudld preallocate it but when I do I get an error end legend('Without Deflection','With Deflection'); hold off

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Answer by Walter Roberson on 8 Dec 2012

getframe() returns a movie frame, which is a struct. You cannot store a struct into a scalar double location such as M(i) where M has been initialized to zeros(1,100)

http://www.mathworks.com/help/matlab/ref/getframe.html

What are you going to do with the frames after you get them? If you are going to create a video, then see the documentation for VideoWriter for an example of how to do it.

Lawson Hoover on 8 Dec 2012

Well I was trying to store the frams in one variable and then be able to call up a particular slide, or position, in the movie with a slider or edit box.

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