Error linking against Armadillo using PGI compiler

Question

I want to accelerate a portion of my code using OpenACC to allow it run on GPUs ,but the most of my code uses Armadillo library for the linear algebra. The easiest way that I found to accelerate the code relies on the PGI set of compilers, but it seems that is not so easy to enable the PGI compiler to link against Armadillo. I tried to follow the recommendation here but it does not work for me in the case of the simplified example in the post:

#include <iostream> 
#include <armadillo> 

using namespace std; 
using namespace arma; 

int main(int argc, char** argv) 
  { 
  mat A = randu<mat>(4,5); 
  mat B = randu<mat>(4,5); 

  cout << A*B.t() << endl; 

#if defined(__GNUG__) 
cout << "I say I'm gcc!" << endl; 
#endif 

#if defined(__PGI) 
cout << "I say I'm PGI!" << endl; 
#endif 
  return 0; 
  } 

It is supposed to compiles using pgc++ -U__GNUG__ -o test.x test.cpp . However, I get lots of errors and warnings. I don't know what is going wrong with this, any suggestion will be very appreciated.

The Error message that I get is:

/tmp/pgc++RnBhbTnyXPYy.o: En la función `void arma::blas::gemv<double>(char const*, int const*, int const*, double const*, double const*, int const*, double const*, int const*, double const*, double*, int const*)':
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemvIdEEvPKcPKiS5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0x7c): referencia a `wrapper_sgemv_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemvIdEEvPKcPKiS5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0xcd): referencia a `wrapper_dgemv_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemvIdEEvPKcPKiS5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0x11e): referencia a `wrapper_cgemv_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemvIdEEvPKcPKiS5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0x16c): referencia a `wrapper_zgemv_' sin definir
/tmp/pgc++RnBhbTnyXPYy.o: En la función `void arma::blas::gemm<double>(char const*, char const*, int const*, int const*, int const*, double const*, double const*, int const*, double const*, int const*, double const*, double*, int const*)':
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemmIdEEvPKcS3_PKiS5_S5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0x8e): referencia a `wrapper_sgemm_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemmIdEEvPKcS3_PKiS5_S5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0xf1): referencia a `wrapper_dgemm_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemmIdEEvPKcS3_PKiS5_S5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0x154): referencia a `wrapper_cgemm_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4gemmIdEEvPKcS3_PKiS5_S5_PKT_S8_S5_S8_S5_S8_PS6_S5_+0x1b4): referencia a `wrapper_zgemm_' sin definir
/tmp/pgc++RnBhbTnyXPYy.o: En la función `double arma::blas::dot<double>(unsigned int, double const*, double const*)':
test.cpp:(.gnu.linkonce.t._ZN4arma4blas3dotIdEET_jPKS2_S4_+0x34): referencia a `wrapper_sdot_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas3dotIdEET_jPKS2_S4_+0x61): referencia a `wrapper_ddot_' sin definir
/tmp/pgc++RnBhbTnyXPYy.o: En la función `void arma::blas::syrk<double>(char const*, char const*, int const*, int const*, double const*, double const*, int const*, double const*, double*, int const*)':
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4syrkIdEEvPKcS3_PKiS5_PKT_S8_S5_S8_PS6_S5_+0x73): referencia a `wrapper_ssyrk_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma4blas4syrkIdEEvPKcS3_PKiS5_PKT_S8_S5_S8_PS6_S5_+0xbb): referencia a `wrapper_dsyrk_' sin definir
/tmp/pgc++RnBhbTnyXPYy.o: En la función `void arma::lapack::gesv<double>(int*, int*, double*, int*, int*, double*, int*, int*)':
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gesvIdEEvPiS2_PT_S2_S2_S4_S2_S2_+0x61): referencia a `wrapper_sgesv_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gesvIdEEvPiS2_PT_S2_S2_S4_S2_S2_+0x99): referencia a `wrapper_dgesv_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gesvIdEEvPiS2_PT_S2_S2_S4_S2_S2_+0xcc): referencia a `wrapper_cgesv_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gesvIdEEvPiS2_PT_S2_S2_S4_S2_S2_+0xff): referencia a `wrapper_zgesv_' sin definir
/tmp/pgc++RnBhbTnyXPYy.o: En la función `void arma::lapack::gels<double>(char*, int*, int*, int*, double*, int*, double*, int*, double*, int*, int*)':
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gelsIdEEvPcPiS3_S3_PT_S3_S5_S3_S5_S3_S3_+0x7c): referencia a `wrapper_sgels_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gelsIdEEvPcPiS3_S3_PT_S3_S5_S3_S5_S3_S3_+0xcd): referencia a `wrapper_dgels_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gelsIdEEvPcPiS3_S3_PT_S3_S5_S3_S5_S3_S3_+0x11e): referencia a `wrapper_cgels_' sin definir
test.cpp:(.gnu.linkonce.t._ZN4arma6lapack4gelsIdEEvPcPiS3_S3_PT_S3_S5_S3_S5_S3_S3_+0x16c): referencia a `wrapper_zgels_' sin definir

Answer 1

The undefined reference messages here are linker errors , which means that the linker couldn't find anywhere the implementation (the compiled code) for some functions used in your program.

Third-party functions are usually provided in the form of some library-file installed on your system. For each such additional library you use, an additional option of the form -lLIBRARY_NAME is to be included in the build command.

The most likely problem here is that you need to add such an option to your build command: -larmadillo .

In case this doesn't work (if the Armadillo library-files were not installed in the usual library directories), you may want to read the Armadillo FAQ for other possible solutions.