zgeevx undefined

[Gregory Tucker]

Attempting to compile a FORTRAN program which calls ZGEEVX from the LAPACK library results in the error "undefined reference to `zgeevx_'" on a machine running Ubuntu 12.04 (liblapack-dev 3.3.1-1) while the same code compiles successfully on two different machines; one Ubuntu 10.04.3 (liblapack-dev 3.2.1-2) and the other Linux Mint Debian (liblapack-dev 3.3.1-1).

[Jason Conti (jconti)]

Thanks for the bug report. Could you please provide a sample file and the command line used to compile it where it fails with the above error?

I am not very familiar with fortran, but my guess is this has to do with the linking changes in 11.10+. I just compiled: http://www.physics.orst.edu/~rubin/nacphy/lapack/codes/eigen-f.html on 12.04 using the command line:

gfortran test.f90 -llapack;

and it compiles without errors. However using:

gfortran -llapack test.f90;

will fail with the error above, because of the linker changes (but will succeed on 10.04). If this is the problem, see http://wiki.debian.org/ToolChain/DSOLinking for a quick overview of the changes.

[Gregory Tucker (gregory-tucker)]

Thanks for the information regarding linking changes. As you assumed the structure of the call to gfortran was incorrect. Changing the Makefile instruction from

gfortran file.f90 -o program_name -llapack $(object_files)

to

gfortran file.f90 -o program_name $(object_files) -llapack

fixed the issue. Thanks again for your help.