Matrix input/output to a Matlab function block in simulink

I need help creating a MATLAB function block in simulink. How do i make a MATLAB function block take in a large matrix from the workspace as its input (say a 1000 by 15 matrix), and also give its output as a matrix?

[Mathieu NOE]

hi

simply creat that input matrix in the workspace (do it from a maytlab script if needed)

if that matrix is "A" then in simulink use the constant bloc or DSP constant block with A as argument (edit box)

now what you do in the simulink file must be coherent with a matrix input ... not every bloc / function accept m by n size inputs.

[Femi Bolarinwa]

Thanks

Answer 1

[Ameer Hamza]

An alternate way is to create a parameter input in the MATLAB function block and give it the same name as the base workspace variable. Refer to Kaustubha's answer here: https://www.mathworks.com/matlabcentral/answers/40701-using-workspace-data-in-matlab-function-block-simulink and follow the instructions after "Besides TAB's solution, ...". Following link will also be helpful

https://www.mathworks.com/help/simulink/ug/parameter-arguments-in-matlab-function-block-functions.html

A slight advantage is that you don't need to create an additional block in your model.

[Femi Bolarinwa]

So im tryting to feed the output of the MATLAB function block to another MATLAB function block. I keep getting this error:

"The signal at 'Input Port 1' of 'xxxx' is a variable-size signal with a nondiscrete sample time. The sample time for any variable-size signal must be discrete."

The output of the first block is 1000 by 1, no time series.

[Ameer Hamza]

Can you show your block diagran?

[Femi Bolarinwa]

So the first MATLAB function block takes in 1000*15 matrix as parameter input like you suggested. The output "CalcLoad" is 1000*1 and X is 12*1. The eventaul output X_f is also 12*1. There is no sample time, just matrix operation but MATLAB keep insisting there must be a discrete sample time.

[Ameer Hamza]

You may try to change the solver mode from variable to discrete. Click the solver name at the lower right corner of the Simulink window. Click the solver setting button, and in the solver selection menu, select "Fixed-step".

[Femi Bolarinwa]

Thanks a lot

Answer 2

[Fangjun Jiang]

Use a Constant block, specify the value as the variable in the base workspace, then you will be able to use it, no matter what is the size of the matrix. When you construct the code for the MATLAB Function block, click the "Edit Data" button and specify the size of input and output variable.

[Femi Bolarinwa]

Thanks. This worked too