Simulink Matlab Function block

Question

Jeremy 2013-12-17

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https://ww2.mathworks.cn/matlabcentral/answers/110060-simulink-matlab-function-block

评论： Sunandan Adhikary 2021-2-7

I have a Matlab workspace variable called clock_frequency.

I use this variable as a parameter in many of my simulink blocks.

I want to be able to access and alter this variable within my Simulink Matlab Function block, but I cannot do it successfully. Unlike the other simulink blocks (that can see the workspace variables) the matlab function block cannot.

I do not want to create a port and pass the variable in as a signal for various reasons.

Reading through the documentation, I have to use data store memory, but this doesn't seem to work. I got a partial version of this working, and the simulink model began running really slowly.

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Answer 1

Niklas Nylén 2013-12-18

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https://ww2.mathworks.cn/matlabcentral/answers/110060-simulink-matlab-function-block#answer_118719

在 MATLAB Online 中打开

This function will read the value x from the base workspace, add 3 to it and write back the new value to the workspace as x. On the next iteration it will read the new value of x and so on.

function y = fcn()
%#codegen
coder.extrinsic('evalin', 'assignin')
x = 0;                  % Needed in order to set variable class correctly
x = evalin('base','x'); % Read value from workspace
y = x+3;                
assignin('base','x',y); % Assign value back to workspace

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Sinan Ibrahim Bayraktar 2019-3-16

I get an error while using it for a maxtrix. Is there a way to access this matrix even if I don't want to change it?

N/A 2020-10-13

在 MATLAB Online 中打开

I believe you could define the matrix with zeros before using 'evalin'. For instance, if you want to import a matrix 'x' that is 2X3 in size, define the following in place of fourth line above.

x=zeros(2,3);

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Answer 2

Rubem Pacelli 2019-8-1

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https://ww2.mathworks.cn/matlabcentral/answers/110060-simulink-matlab-function-block#answer_385817

编辑：Rubem Pacelli 2019-8-1

There are another solution for your question.

Double-click in the MATALAB function block. Will open a script function of your "MATALAB function" block
click on edit data
click on add -> data (or just type cntrl+D shortcut keyword)
type the same name of the variable tha you want pass to MATLAB function block
In Scope, choose "Parameter" option.

It's work fine in my computer. You need save your variable in the MATLAB workspace.

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mohammad nojavan 2020-8-20

hi rubem i dowloaded a simulink file from internet tath contaies some of " Data store Memory block's" . if i want to change the value of this block they dont change and when i run the simulink file the value of data store memory blocks comeback the initial values. please help me

elec.engeen2011@gmail.com

Sunandan Adhikary 2021-2-7

This way we n import the variable but it does not get updated! I am trtying to update arrays in a structure and everytime it enters the function it updates that particular indexec position but later when the function is called in next iteration, those values are gone from the array.

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