The extrinsic function 'horzcat' is not available for standalone code generation. It must be eliminated for stand-alone code to be generated. It could not be eliminated becaus

Thanks Jan for your answer.

My mfile is now converted to MEX but can not generate a C/C++ sourse code using GPU Coder APP, giving the following error.

"The extrinsic function 'horzcat' is not available for standalone code generation. It must be eliminated for stand-alone code to be generated. It could not be eliminated because its outputs appear to influence the calling function. Fix this error by not using 'horzcat' or by ensuring that its outputs are unused."

I looked it up in myfile.cu and commmented out //horzcats but no success.

Any ideas?

[Jan]

You are welcome. I assume, you mean an answer in another thread?

Can you post the code?

[Ram Kokku]

@Fatemeh - horzcat is supported for code generation. here the doc for it https://www.mathworks.com/help//matlab/ref/double.horzcat.html.

Are you using coder.extrensic function anywhere? would you be able to share the problematic code snippet?

[Fatemeh Kalantari]

Thanks for your help.

Answer 1

[Hariprasad Ravishankar]

Its very likely that you have a coder.extrinsic function defined on horzcat as follows:

function out = foo(a,b)
coder.extrinsic('horzcat');
out = horzcat(a,b);
end

>> codegen -args {ones(5,4), ones(5,4)} foo -config:dll
The extrinsic function 'horzcat' is not available for standalone code generation. It must be eliminated for stand-alone code to be
generated. It could not be eliminated because its outputs appear to influence the calling function. Fix this error by not using
'horzcat' or by ensuring that its outputs are unused.

For MEX code generation, coder.extrinsic calls back into MATLAB runtime to compute the horzcat function. However, for standalone code generation, we don't have MATLAB to call back into, so we see this error.

As my colleague Ram mentioned, since horzcat is supported for code generation, you can remove the coder.extrinsic pragma.

function out = foo(a,b)
out = horzcat(a,b);
end

>> codegen -args {ones(5,4), ones(5,4)} foo -config:dll
Code generation successful.

[Fatemeh Kalantari]

Thanks for your help.

I need to check the time the generated MEX file takes to run and compare it to its equivalent mfile but "tic;myfile;toc" is not responding. Do you have any suggestions for me. Also how can I generate the myfile_gpu extension and compare the timing?

[Hariprasad Ravishankar]

Can you clarify a bit more about tic; .. toc now responding? Is "myfile" a M function or the generated MEX?

[Fatemeh Kalantari]

Yes, It worked apparently the code showing the timing for mex file generated from mfile is:

tic;myfile().mex;toc

from myfile.m we will generate myfile.mex

Still not clarified on how to generate the _gpu extension using GPU Coder app?

[Ram Kokku]

Hi Fatemeh,

MATLAB Coder and GPU Coder both generate same extension for MEX files, i.e mexa64 (or something similar based on your platform). if you want to confirm if the MEX was generated for GPU or CPU, take a look at the generated files located in codegen/mex/<your design name>. For GPU Coder, you should find .cu files in this directory.

Take a look at this video Using GPU coder to generate Cuda code from Matlab - YouTube.

for Simulink: Deep Learning in Simulink for NVIDIA GPUs: Generate CUDA Code Using GPU Coder - YouTube

Answer 2

[Walter Roberson]

Does the same problem occur if you use [] notation?

horzcat(a,b)
[a,b]

should be the same. Maybe it only allows [] with constants?

You could also try

cat(2,a,b)