failure to link atlas

[vimsical]

I have these packages install:

$ apt-policy libatlas-{base-,}dev
libatlas-base-dev:
Installed: 3.8.4-3build1
Candidate: 3.8.4-3build1
Version table:
*** 3.8.4-3build1 0
500 http://us.archive.ubuntu.com/ubuntu/ precise/universe amd64 Packages
100 /var/lib/dpkg/status
libatlas-dev:
Installed: 3.8.4-3build1
Candidate: 3.8.4-3build1
Version table:
*** 3.8.4-3build1 0
500 http://us.archive.ubuntu.com/ubuntu/ precise/universe amd64 Packages
100 /var/lib/dpkg/status


and I am trying to compile this test program:

#include <atlas/clapack.h>


int main() {
int n = 2, m=3;
double a_v[] = {1, 4, 2, 3};
double b_v[] = {1, 2, 3, 4, 5, 6};
int status = clapack_dposv(CblasRowMajor, CblasUpper, n, m, a_v, n, b_v, n);
}


But I got a linker error:

gcc proto/atlas_test.c -o atlas_test -L/usr/lib/atlas-base/ -latlas -lcblas
/tmp/ccoG7mea.o: In function `main':
atlas_test.c:(.text+0xd3): undefined reference to `clapack_dposv'
collect2: ld returned 1 exit status


I tried to use nm to see where the symbol clapack_dposv in various library files in /usr/lib/atlas-base/, but they all seem to have no exported symbol. Any help and suggestion are appreciated.

[steeldriver]

I admit to finding the whole atlas/blas/lapack thing confusing - however I think it's correct to say that atlas just provides alternative versions of the regular blas and lapack libraries i.e.



$ update-alternatives --get-selections | grep 'blas\|lapack'
libblas.so auto /usr/lib/atlas-base/atlas/libblas.so
libblas.so.3 auto /usr/lib/atlas-base/atlas/libblas.so.3
liblapack.so auto /usr/lib/atlas-base/atlas/liblapack.so
liblapack.so.3 auto /usr/lib/atlas-base/atlas/liblapack.so.3


In other words, all that should be necessary is to verify that your update-alternatives are set correctly - if not, you can use



sudo update-alternatives --config libblas.so

sudo update-alternatives --config liblapack.so


and then


gcc -o atlas_test atlas_test.c -lblas -llapack

[vimsical]

Thanks you!