How do I generate code with OpenBLAS routines in MATLAB Coder on Linux?

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I am running MATLAB on Linux, and I have a MATLAB function, simplefn, shown below:
function [outputArg1] = simplefn(inputArg1,inputArg2) outputArg1 = inputArg1 * inputArg2; end
When I generate code for this function, I see code as follows in simplefn.c:
void simplefn(const double inputArg1[1000000], const double inputArg2[1000000],        double outputArg1[1000000]) {  double d;  int i;  int i1;  int i2;  for (i = 0; i < 1000; i++) {   for (i1 = 0; i1 < 1000; i1++) {    d = 0.0;    for (i2 = 0; i2 < 1000; i2++) {     d += inputArg1[i + 1000 * i2] * inputArg2[i2 + 1000 * i1];    }    outputArg1[i + 1000 * i1] = d;   }  } }
However, I want the generated code to use OpenBLAS routines. How do I accomplish this?

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 24 Jan 2025
Edited: MathWorks Support Team on 3 Feb 2025
To generate code for 'simplefn' using OpenBLAS routines, first define a MATLAB class openblascallback.m as shown below. This example is adapted from the documentation. Note that the library shared object and header locations, as well as the header name, depend on the Operating System and the specific BLAS library or package installed. For detailed instructions, you can access the release-specific documentation by executing the following command in the MATLAB R2020b command window:
>> web(fullfile(docroot, 'coder/ref/coder.blascallback-class.html'))
classdef openblascallback < coder.BLASCallback methods (Static) function updateBuildInfo(buildInfo, buildctx) libPriority = ''; libPreCompiled = true; libLinkOnly = true; libName = 'libopenblas.so'; libPath = fullfile('/usr/lib/x86_64-linux-gnu'); incPath = fullfile('/usr/include/x86_64-linux-gnu'); buildInfo.addLinkFlags('-lpthread'); buildInfo.addLinkObjects(libName, libPath, ... libPriority, libPreCompiled, libLinkOnly); buildInfo.addIncludePaths(incPath); end function headerName = getHeaderFilename() headerName = 'cblas.h'; end function intTypeName = getBLASIntTypeName() intTypeName = 'blasint'; end end end
Then create the following Code Generation script simplefn_script.m:
% SIMPLEFN_SCRIPT Generate static library simplefn from simplefn. % % Script generated from project 'simplefn.prj' on 04-Dec-2020. % % See also CODER, CODER.CONFIG, CODER.TYPEOF, CODEGEN. %% Create configuration object of class 'coder.EmbeddedCodeConfig'. cfg = coder.config('lib', 'ecoder', false); cfg.GenerateReport = true; cfg.Toolchain = 'GNU gcc/g++ | gmake (64-bit Linux)'; cfg.CustomBLASCallback = 'openblascallback'; %% Invoke MATLAB Coder. codegen -config cfg simplefn -args {zeros(1000),zeros(1000)} -report
Running simplefn_script.m should successfully generate code with OpenBLAS routines. The simplefn.c now contains:
void simplefn(const double inputArg1[1000000], const double inputArg2[1000000], double outputArg1[1000000]) { cblas_dgemm(CblasColMajor, CblasNoTrans, CblasNoTrans, (blasint)1000, (blasint) 1000, (blasint)1000, 1.0, &inputArg1[0], (blasint)1000, &inputArg2[0], (blasint)1000, 0.0, &outputArg1[0], (blasint)1000); }
Please follow the link below to search for the required information regarding the current release:
  2 Comments
Ryan Livingston
Ryan Livingston on 10 Jan 2021
Edited: Ryan Livingston on 10 Jan 2021
Using BLAS via the CustomBLASCallback property does not require Embedded Coder. You can change the script to accommodate that:
cfg = coder.config('lib','ecoder',false);
cfg.GenerateReport = true;
cfg.Toolchain = 'GNU gcc/g++ | gmake (64-bit Linux)';
cfg.CustomBLASCallback = 'openblascallback';
A simple way to see if a Coder config setting requires Embedded Coder is to see if it present in the coder.CodeConfig class
or only in the coder.EmbeddedCodeConfig class
CustomBLASCallback is in the former, so it does not require Embedded Coder.

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