Embedded Matlab function to save a random number

Question

Owen 2012-10-23

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Hi,

I want to write an Embedded Matlab function to store the ramdom number of the Random Generator block into a vector, something like 'To Workspace' block.

The code is following: function fcn(u) eml.extrinsic('assignin'); eml.extrinsic('evalin'); % index initialization persistent index; if isempty(index) index = 0; end;

% every time a new index
index = index + 1;
% save the variables in workspace
assignin('caller', 'a', u);
assignin('caller', 'b', uint16(index));
evalin('caller', 'c(uint16(b)) = a');

The variable 'c' is defined in a function which runs the 'sim()' command. c = zeros(1000, 1);

There is an error: In an assignment A(I) = B, the number of elements in B and I must be the same.

which relates to this line:

evalin('caller', 'c(uint16(b)) = a');

Could anybody help me to solve this problem?

Thanks Senmeis

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Answer 1

Kaustubha Govind 2012-10-23

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https://ww2.mathworks.cn/matlabcentral/answers/51642-embedded-matlab-function-to-save-a-random-number#answer_62952

编辑：Kaustubha Govind 2012-10-23

在 MATLAB Online 中打开

Is 'u' a non-scalar value? If yes, this is expected. For example:

>> c(uint16(4)) = [0 0]
In an assignment  A(I) = B, the number of elements in B and I must be the same.

If you plan to assign a vector to create a 2-D matrix C, you should probably use the colon operator:

>> c(uint16(4),:) = [1 2]
c =
       0     0
       0     0
       0     0
       1     2

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Answer 2

Owen 2012-10-24

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https://ww2.mathworks.cn/matlabcentral/answers/51642-embedded-matlab-function-to-save-a-random-number#answer_63083

The problem is solved. The error is because the Random Number Generator block generates frame based data. A Buffer block of length 1 is inserted and everything becomes OK.

Are there any other blocks that convert nx1 vectors to 1x1 vectors besides Buffer block?

Thanks Senmeis

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Kaustubha Govind 2012-10-24

Does the "Random Number Generator" block have a dialog setting to change it from frame-based data to sample-based data? That might be the right thing to do here.

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