variable size of simulink matlab function

function desired = path_planning(data_points,slope0,slopeF,dt)
t_dummy=0:((length(data_points))-1);
tq=0:(dt/10):((length(data_points))-1);
desired=spline(t_dummy,[slope0; data_points; slopeF],tq);
end

error "Data 'desired' is inferred as a variable size matrix, while its properties in the Model Explorer specify its size as inherited or fixed. Please check the 'Variable Size' check box and specify the upper bounds in the size field."

i am also attaching the simulink file, can you please see what is issue here? the same function works fine in matlab but not in simulink.

Answer 1

[Birdman]

Run the attached model. What you basically needed to do is to go to Model Explorer and set the output of the MATLAB Function as variable size by checking the tickbox there. Also, specify the size of the output.

[Syed hamza Ali Tirmizi]

Not working.... the point to think is, data_points are variable input vector, it's length will define the size of output vector.... so how can i tell the simulink it's size beforehand in model explorer?

[Birdman]

It worked for me without any error. Are you sure it is not working?

Yes, you can tell it by writing

 str2num(get_param('open_loop_for_matlab_edited/Constant3','Value'))

[Syed hamza Ali Tirmizi]

this error pops up

[Birdman]

Run this.

[Syed hamza Ali Tirmizi]

same error, it seems increasing size don't matter here. Also Simulink is not handling varsize of array.

[Birdman]

What is the code in your MATLAB Function?

[Syed hamza Ali Tirmizi]

function desired = path_planning(data_points,slope0,slopeF,dt)
t_dummy=0:((length(data_points))-1);
tq=0:(dt/10):((length(data_points))-1);
desired=spline(t_dummy,[slope0; data_points; slopeF],tq);
end

[Birdman]

Add this line to your function at the very beginning. Also, check the attached figure to make sure your Model Explorer contains the necessary information.

function desired = path_planning(data_points,slope0,slopeF,dt)
desired=zeros(data_points(1),data_points(2));
t_dummy=0:((length(data_points))-1);
tq=0:(dt/10):((length(data_points))-1);
desired=spline(t_dummy,[slope0; data_points; slopeF],tq);
end

[Syed hamza Ali Tirmizi]

not working, but i need to say thank you.

[Birdman]

Have you checked my attached figure? Have you verified that it is the same as yours? Check for the model and block name match.

[Syed hamza Ali Tirmizi]

yeah i matched that too

[Birdman]

There you see your model's name is open_loop_for_matlab but in size field, the model name is open_loop_for_matlab_reedited. Erase the _reedited part to match the model name with the content of get_param. Note that they should be matching at every letter. Try this.

[Syed hamza Ali Tirmizi]

they are matching now, still same error

[Syed hamza Ali Tirmizi]

error

[Birdman]

hamza's answer moved here:

thanks Birdman, i got a solution from this discussion. i first need to define var size where you asked me to. So it outputs the correct results.

[Birdman]

You are welcome. Actually, there was nothing else I could suggest because it should have worked with the way that I suggested. Anyway, I am glad it works.

Answer 2

[Lavanya Dachepally]

The same question but in my case I need to check that variable size and specify its size through commands.

I have connected to the function block to the model through commands and the output of the function comes into picture when I ran code which is of variable based on the input.

Please can some one help how to check the box and specify its size through some commands.