MATLAB Codegen Compiler Error

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Lawrence Costa
Lawrence Costa on 23 Mar 2018
Answered: Raghu Boggavarapu on 26 Nov 2021
Hi,
I am using attempting to convert MATLAB code to c using codegen. This works fine when I convert to mex directly. However, when I 1) use codegen to generate c files then 2) attempt to generate a mex file from the c files (using the mex command), I get the following error:
"Error using mex Undefined symbols for architecture x86_64:
[several dozen reference errors]
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)"
Is there a reason why this would work directly from the codegen command but fail when I attempt to do it step-wise? I am on a mac running High Sierra 10.13.3 with MATLAB 2017b.
Thanks for the help.
Update: Here is an example using the standard MATLAB interp1 function.
n = 130;
x = linspace(0,50,n)';
y = x.^2;
query = 27.5;
codegen interp1 -args {x,y,query}
If, instead of using interp1_mex, I attempt to use the generated c file directly, I get an error. The command
mex interp1.c
returns the error
Error using mex
Undefined symbols for architecture x86_64:
"_b_error", referenced from:
_interp1 in interp1.o
"_error", referenced from:
_interp1 in interp1.o
"_mexFunction", referenced from:
-exported_symbol[s_list] command line option
"_muDoubleScalarIsNaN", referenced from:
_interp1 in interp1.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
  4 Comments
Walter Roberson
Walter Roberson on 13 Apr 2018
When you use mex without any options, it expects that the source you list is a function written to mex standards, for the purpose of calling the code directly from MATLAB. To compile stand-alone code for use outside of MATLAB you need to either compile outside of the mex toolchain, or else use some of the options to mex, such as -client

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Answers (1)

Raghu Boggavarapu
Raghu Boggavarapu on 26 Nov 2021
Write a new MATLAB function using coder.cinclude and coder.ceval to call the generated c function. User coder.updateBuildInfo to link the autogenerated library and also to reference the generated code directory for include paths. Now use MATLAB Coder to generate MEX for this newly written function.

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