simulink function block error: Function output 'y' cannot be an mxArray in this context.

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Jiang Ping 2019-1-6

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https://ww2.mathworks.cn/matlabcentral/answers/438460-simulink-function-block-error-function-output-y-cannot-be-an-mxarray-in-this-context

评论： Jiang Ping 2019-1-9

i am dealing with a function block in simulink, trying to calculate the interval of a signal with variable frequency to get the real time frequency. My thought is to use tic/toc get the interval between two peaks.

So confused by this error. The diagnostic says:

Function output 'y' cannot be an mxArray in this context. Consider preinitializing the output variable with a known type. Function 'MATLAB Function1' (#312.9.10), line 1, column 10: "y" Launch diagnostic report.

Simulink cannot determine sizes and/or types of the outputs for block 'signalTimer/MATLAB Function1' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

function y = timer(u)
coder.inline('never');
coder.extrinsic('toc')
coder.extrinsic('tic')
persistent x1 x2
% x1=0;
% x2=0;
if isempty(x1)
    x1 = 0;
    x2 = 0;
else
x2=x1;
end
x1=u;
if  x1<x2
    y=toc;
    y=double(y);
    tic
end
end

2 个评论
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Vishal Chaudhary 2019-1-9

"tic' must be called without an output argument before calling "toc".

Documentation for tic: https://www.mathworks.com/help/matlab/ref/tic.html

Jiang Ping 2019-1-9

Thank you, but this problem can be addressed if I execute tic in the command line before run the script. Actually what I am really want to do is to measure the frequency of sqaure wave whose frequency is variable in real time .

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