Armadillo C++ configuration Check

Question

Is there a way to check the configuration of armadillo from a c++ program? I just want to make sure armadillo has been compiled with 'atlas' or 'openblas'

I found arma::arma_config cfg; but I have no idea what cfg contains. I've done some testing and found blas and atlas but openblas does not seem to be an option. Is there anywhere I can find a complete list of what cfg contains?

Answer 1

That is common misunderstanding. Armadillo uses the LAPACK/BLAS interface and you can switch the libraries out at will.

edd@rob:/tmp$ g++ -o armadillo_example armadillo_example.cpp -larmadillo
edd@rob:/tmp$ ./armadillo_example 
A*trans(B) =
  -0.3111  -0.3320  -0.8700  -0.8698
   0.1312  -0.7760  -0.2394  -0.6150
  -0.2320  -1.2993  -0.6748  -1.3584
  -0.1677  -1.9175   0.6289  -0.5619

edd@rob:/tmp$ ldd armadillo_example
        linux-vdso.so.1 (0x00007fff92b5b000)
        libarmadillo.so.9 => /usr/lib/libarmadillo.so.9 (0x00007fe598ea5000)
        libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fe598cc4000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fe598b75000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fe598b5a000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fe598970000)
        libblas.so.3 => /usr/lib/x86_64-linux-gnu/libblas.so.3 (0x00007fe598910000)
        liblapack.so.3 => /usr/lib/x86_64-linux-gnu/liblapack.so.3 (0x00007fe598271000)
        libarpack.so.2 => /usr/lib/x86_64-linux-gnu/libarpack.so.2 (0x00007fe598229000)
        libsuperlu.so.5 => /usr/lib/x86_64-linux-gnu/libsuperlu.so.5 (0x00007fe5981b9000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fe598ef1000)
        libopenblas.so.0 => /usr/lib/x86_64-linux-gnu/libopenblas.so.0 (0x00007fe596025000)
        libgfortran.so.5 => /usr/lib/x86_64-linux-gnu/libgfortran.so.5 (0x00007fe595d5d000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fe595d39000)
        libquadmath.so.0 => /usr/lib/x86_64-linux-gnu/libquadmath.so.0 (0x00007fe595cef000)
edd@rob:/tmp$ 

The armadillo shared library has similar links:

edd@rob:/tmp$ ldd /usr/lib/libarmadillo.so.9
        linux-vdso.so.1 (0x00007ffc98853000)
        libblas.so.3 => /usr/lib/x86_64-linux-gnu/libblas.so.3 (0x00007f6043563000)
        liblapack.so.3 => /usr/lib/x86_64-linux-gnu/liblapack.so.3 (0x00007f6042ec6000)
        libarpack.so.2 => /usr/lib/x86_64-linux-gnu/libarpack.so.2 (0x00007f6042e7e000)
        libsuperlu.so.5 => /usr/lib/x86_64-linux-gnu/libsuperlu.so.5 (0x00007f6042e0e000)
        libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f6042c2d000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f6042ade000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f6042ac1000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f60428d7000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f60435ff000)
        libopenblas.so.0 => /usr/lib/x86_64-linux-gnu/libopenblas.so.0 (0x00007f6040743000)
        libgfortran.so.5 => /usr/lib/x86_64-linux-gnu/libgfortran.so.5 (0x00007f604047b000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f6040459000)
        libquadmath.so.0 => /usr/lib/x86_64-linux-gnu/libquadmath.so.0 (0x00007f604040d000)
edd@rob:/tmp$ 

On my Ubuntu system /usr/lib/x86_64-linux-gnu/libblas.so.3 is a softlink that gets updated when another BLAS/LAPACK package is installed allowing you to easil switch (which I use e.g. in this GitHub repo to show how to easily install MKL.