I work on an Ubuntu 16.04 LTS system, which comes with native gcc-5 and gfortran-5 compilers. I am working on building a project, that recommends gfortran 6.3 and above. So I installed the PPA Test Toolchain and downloaded gcc-7 and gfortran-7 compilers. And made them system default.
My program uses Lapack and Blas libraries as well, which I downloaded via apt-get (Synaptic package manager).
$ gfortran --version GNU Fortran (Ubuntu 7.2.0-1ubuntu1~16.04) 7.2.0 Copyright (C) 2017 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ gcc --version gcc (Ubuntu 7.2.0-1ubuntu1~16.04) 7.2.0 Copyright (C) 2017 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. However, when compiling the program, I get the following warning:
/usr/bin/ld: warning: libgfortran.so.3, needed by /usr/lib/lapack/liblapack.so, may conflict with libgfortran.so.4 libgfortran.so.3
$ strings /usr/lib/gcc/x86_64-linux-gnu/5.4.1/libgfortran.so | grep "GFORTRAN_" GFORTRAN_1.0 GFORTRAN_1.1 GFORTRAN_1.2 GFORTRAN_1.3 GFORTRAN_1.4 GFORTRAN_1.5 GFORTRAN_1.6 GFORTRAN_1.7 GFORTRAN_C99_1.0 GFORTRAN_C99_1.1 GFORTRAN_STDIN_UNIT GFORTRAN_STDOUT_UNIT GFORTRAN_STDERR_UNIT GFORTRAN_UNBUFFERED_ALL GFORTRAN_SHOW_LOCUS GFORTRAN_OPTIONAL_PLUS GFORTRAN_DEFAULT_RECL GFORTRAN_LIST_SEPARATOR GFORTRAN_CONVERT_UNIT GFORTRAN_ERROR_BACKTRACE GFORTRAN_UNBUFFERED_PRECONNECTED libgfortran.so.4
$ strings /usr/lib/gcc/x86_64-linux-gnu/7.2.0/libgfortran.so | grep "GFORTRAN_" GFORTRAN_7 GFORTRAN_F2C_7 GFORTRAN_C99_7 GFORTRAN_STDIN_UNIT GFORTRAN_STDOUT_UNIT GFORTRAN_STDERR_UNIT GFORTRAN_UNBUFFERED_ALL GFORTRAN_SHOW_LOCUS GFORTRAN_OPTIONAL_PLUS GFORTRAN_DEFAULT_RECL GFORTRAN_LIST_SEPARATOR GFORTRAN_CONVERT_UNIT GFORTRAN_ERROR_BACKTRACE GFORTRAN_UNBUFFERED_PRECONNECTED Is there a way to force (and I am using this term loosely as I am new to this and maybe overlooking something obvious) the lapack and blas libraries to use gfortran-7?
