unexpected matlab operator error when plotting from a simulink matlab function

Question

Alberto 2023-1-18

0
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https://ww2.mathworks.cn/matlabcentral/answers/1896435-unexpected-matlab-operator-error-when-plotting-from-a-simulink-matlab-function

编辑： Alberto 2023-1-19

Hi to everyone,

I have a matlab function called from simulink and I'm trying to plot all the elements of a vector, but unexpected matlab operator error appears.

My aim is to build a vector adding [u,u] at each step (like vector=[vector;x]) and then plot it at the end of each step.

I don't know why it doesn't accept the ":" in the plot.

The code is:

function fcn(u)

coder.extrinsic('evalin', 'assignin', 'plot')

if u==0

xx=[u,u];

assignin('base','xx',xx);

sz=size(xx);

assignin('base','sz',sz);

else

sz=zeros(1,2);

szz=evalin('base','sz');

xx=zeros(szz(1),szz(2));

xxx=evalin('base','xx');

xx=[xxx;[u,u]];

assignin('base','xx',xx);

end

figure(1)

plot(xx(:,1),xx(:,2),'ko');

end

Does anyone know how to fix it?

Thanks!

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Answer 1

Paul 2023-1-19

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https://ww2.mathworks.cn/matlabcentral/answers/1896435-unexpected-matlab-operator-error-when-plotting-from-a-simulink-matlab-function#answer_1151595

在 MATLAB Online 中打开

Hi Edoardo,

Are you really trying to plot u vs. u? Wouldn't that just be a straight line?

If I understand what you're trying to do, would the XY Graph be applicable?

If wanting to do this in a Matlab Function, this code worked for me. It seems simpler and doesn't have to work with the base workspace.

function fcn(t,u)
% Incrementally add points to a line plot of t vs u
persistent init hline
if isempty(init)
    init = 1;
    figure;
    hline = line(gca,t,u);
else
set(hline,'XData',[get(hline,'XData') t]);
set(hline,'YData',[get(hline,'YData') u]);
end
end