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230 lines
11 KiB
Markdown
230 lines
11 KiB
Markdown
Building the NetCDF-4.2 and later Fortran libraries {#building_netcdf_fortran}
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===================================================
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[TOC]
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In versions before 4.2, the Fortran netCDF library source was bundled
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with the C library source in one distribution. With more recent
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versions, the Fortran netCDF library has been split off into an
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independent source distribution, intended to be built as a separate
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library, *after* the C library is built and installed. This separation
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simplifies the building and use of the C and Fortran netCDF libraries
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and allows them to evolve independently.
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More recently, building netcdf-fortran as an automated step in the
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netcdf-c build is now possible (for non-MSVC builds) by using new
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options at configure time, so if you haven't built and installed the
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netCDF-C library yet, you may want to try the new netCDF-C <a
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href="https://docs.unidata.ucar.edu/netcdf-c/current/getting_and_building_netcdf.html#getting"
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>Fortran-bootstrap procedure</a>.
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In the example commands below, we assume use of a
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POSIX-standard shell, such as sh, bash, ksh, or zsh. If you are using
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csh instead, you will have to use the
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setenv ENV_VARIABLE value
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syntax to set environment variables instead of the
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ENV_VARIABLE=value
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syntax used in the examples. In either case, `${VAR}` is the
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value of the shell variable or environment variable VAR.
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It will be easier to build the netCDF Fortran library if the C (and if
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needed, HDF5) libraries are built as shared libraries (the default), but
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you can also use static libraries, as described in a later section.
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Building with shared libraries {#building_fortran_shared_libraries}
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==============================
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1. First make sure the netCDF C library has been built, tested, and
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installed. The shell variable NCDIR should be set such that
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the shared library for netCDF C is under `${NCDIR}/lib` and
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netCDF utilities such as ncdump are under `${NCDIR}/bin`. For example:
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NCDIR=/usr/local
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2. The configure script will try to determine suitable Fortran and C
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compilers for building netCDF Fortran, but you can instead specify
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them with the FC and CC environment variables, if needed. For
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example:
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CC=/usr/local/cc
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FC=/usr/local/fortran
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3. If the netCDF C library was installed as a shared library in a
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location that is not searched by default, you will need to set the
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LD\_LIBRARY\_PATH environment variable (or DYLD\_LIBRARY\_PATH on
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OSX) to specify that directory before running the configure script.
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For example:
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export LD_LIBRARY_PATH=${NCDIR}/lib:${LD_LIBRARY_PATH}
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4. If you set the LD\_LIBRARY\_PATH (or DYLD\_LIBRARY\_PATH)
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environment variable in the previous step, don't use "sudo"
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before the following "configure" or "make check" commands.
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Using "sudo" causes the LD\_\* environment variables to be
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ignored. You can use "sudo make install" as the last
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step if necessary, but don't use "sudo" before that.
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5. Set the shell variable `NFDIR` to where you want to install
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netCDF Fortran, which can be the same location where the netCDF C
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was installed (default /usr/local), but **not** the source
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directory where you are building the software. Then, from the top-level
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source directory, run the configure script, using CPPFLAGS and LDFLAGS to
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specify where the netCDF C library was installed:
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NFDIR=/usr/local
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CPPFLAGS=-I${NCDIR}/include LDFLAGS=-L${NCDIR}/lib \
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./configure --prefix=${NFDIR}
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If you are cross-compiling, you should also include the configure
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option "--disable-fortran-type-check", as in:
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CPPFLAGS=-I${NCDIR}/include LDFLAGS=-L${NCDIR}/lib \
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./configure --prefix=${NFDIR} --disable-fortran-type-check
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To see other configure options, run `configure --help`.
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6. If that succeeds, run
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make check
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7. If that succeeds, run
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make install
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or
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sudo make install
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If you encounter problems, send the complete "config.log" file
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generated by running configure to support-netcdf@unidata.ucar.edu.
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Building with static libraries {#building_fortran_with_static_libraries}
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==============================
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If you can't build the C netCDF library as a shared library or if it has
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already been installed by someone else only as a static library (which
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means there are no libnetcdf.so files in the library directory where the
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netCDF C library was installed), then building and installing the
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Fortran netCDF libraries will be more complicated.
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1. The configure script will try to determine suitable Fortran and C
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compilers for building netCDF Fortran, but you can also, specify
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them with the FC and CC environment variables.
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2. Assume the static netCDF C library is installed under `${NCDIR}`,
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the HDF5 library under `${H5DIR}`, and other needed libraries
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such as zlib and curl under `${ODIR}`. Some or all of these could
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be the same (for example /usr/local).
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3. Let the shell variable `${NFDIR}` specify where you want to
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install the netCDF Fortran library. This can be the same location
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where the netCDF C library is installed (default is /usr/local).
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4. Set the CPPFLAGS, LDFLAGS, LD\_LIBRARY\_PATH, and LIBS environment
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variables to specify where the netCDF C library is installed and
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where the other libraries may be found. For example:
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CPPFLAGS="-I${NCDIR}/include -I${H5DIR}/include -I${ODIR}/include" \
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LDFLAGS="-L${NCDIR}/lib -L${H5DIR}/lib -L${ODIR}/lib" \
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LD_LIBRARY_PATH=${NCDIR}/lib:${H5DIR}/lib:${ODIR}/lib \
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LIBS="-lnetcdf -lhdf5_hl -lhdf5 -lz -lcurl" \
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./configure --disable-shared --prefix=${NCDIR}
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If you are cross-compiling, you should also include the configure
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option "--disable-fortran-type-check".
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5. For parallel I/O: The configure script sets CFLAGS appropriately for
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standard compilers, but if you are building with parallel I/O using
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wrappers such as mpicc, mpif90, and mpif77, specify compilers
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using the CC, FC, and F77 variables before configure. For example:
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CC=mpicc FC=mpif90 F77=mpif77 CPPFLAGS=-I${NCDIR}/include \
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LDFLAGS=-L${NCDIR}/lib ./configure --prefix=${NFDIR}
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You may have to use absolute path names for CC, F90, and F77 if
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configure can't find them. Finally, you may also need to set
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CFLAGS to indicate which Fortran compiler is wrapped by mpif90 nd
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mpif77. For example, if "mpif90 --show" indicates gfortran is
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being used, then set CFLAGS=-DgFortran, and similarly set
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CFLAGS=-DpgiFortran for Portland Group compilers.
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6. If that succeeds, run "make check".
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7. If that succeeds, run "make install" or "sudo make install".
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If you encounter problems, send the complete "config.log" file
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generated by running configure to support-netcdf@unidata.ucar.edu.
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Linking your programs with netCDF Fortran libraries {#linking_against_netcdf_fortran}
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==============================
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If you built the shared libraries, you can link with something like
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fortran my_prog.f -o my_prog -I${NFDIR}/include -L${NFDIR}/lib -lnetcdff
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to link your Fortran software with the installed netCDF Fortran and C
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libraries.
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If you didn't install the shared libraries in a standard place, you
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may need to set LD\_LIBRARY\_PATH (or DYLD\_LIBRARY\_PATH for OSX) to
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include `${NFDIR}/lib` before running the resulting
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program. Alternatively, you may add `${NFDIR}/lib` to the
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LD\_RUN\_PATH environment variable before linking, or use the
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`-Wl,-rpath -Wl,${NFDIR}/lib` linker flag, or have your system
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administrator add `${NFDIR}/lib` to `/etc/ld.so.conf'. See
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operating system documentation about shared libraries for more
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information, such as the ld(1) and ld.so(8) manual pages.
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If you built static libraries, you will need to use something like
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fortran my_prog.f -o my_prog -I${NFDIR}/include \
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-L${NCDIR}/lib -lnetcdff -lnetcdf \
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-L${H5DIR}/lib -lhdf5_hl -lhdf5 -L${ODIR} -lz -lcurl -lm
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to link Fortran software with the installed Fortran library and the
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libraries on which it depends.
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A simpler alternative that should work for either shared or static
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libraries is to use the "nf-config" utility installed in `${NFDIR}/bin`:
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fortran my_prog.f -o my_prog `nf-config --fflags --flibs`
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or the more general "pkg-config" utility, if you have it:
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fortran my_prog.f -o my_prog `pkg-config --cflags --libs netcdf-fortran`
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Specifying The Environment for Building {#specify_build_env_fortran}
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========================================
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For cross-compiles, the following environment variables can be used to override the default fortran/C type settings like this (in sh):
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export NCBYTE_T="integer(selected_int_kind(2))"
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export NCSHORT_T="integer*2"
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export NF_INT1_T="integer(selected_int_kind(2))"
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export NF_INT2_T="integer*2"
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export NF_INT1_IS_C_SHORT=1
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export NF_INT2_IS_C_SHORT=1
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export NF_INT_IS_C_INT=1
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export NF_REAL_IS_C_FLOAT=1
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export NF_DOUBLEPRECISION_IS_C_DOUBLE=1
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In this case you will need to run configure with `–disable-fortran-compiler-check` and `–disable-fortran-type-check`.
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Environment Variable Description Notes
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--------------------------
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Variable | Usage | Description
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---|---|---
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CC | C compiler | If you don't specify this, the configure script will try to find a suitable C compiler. The default choice is gcc. If you wish to use a vendor compiler you must set CC to that compiler, and set other environment variables (as described below) to appropriate settings.
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FC | Fortran compiler (if any) | If you don't specify this, the configure script will try to find a suitable Fortran and Fortran 77 compiler. Use –disable-f90 to disable the netCDF Fortran 90 API, but build the netCDF Fortran 77 API.
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F77 | Fortran 77 compiler (if any) | Only specify this if your platform explicitly needs a different Fortran 77 compiler. Otherwise use FC to specify the Fortran compiler. If you don't specify this, the configure script will try to find a suitable Fortran compiler. For vendor compilers, make sure you're using the same vendor's Fortran 90 compiler. Using Fortran compilers from different vendors is not supported and may not work.
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CFLAGS | C compiler flags | "-O -g2", for example.
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CPPFLAGS | C preprocessor options | "-DNDEBUG" to omit assertion checks, for example.
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FCFLAGS| Fortran 90 compiler flags | "-O" or "-g", for example. These flags will be used for FORTRAN 90. If setting these you may also need to set FFLAGS for the FORTRAN 77 test programs.
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FFLAGS | Fortran 77 compiler flags | "-O" or "-g", for example. If you need to pass the same arguments to the FORTRAN 90 build, also set FCFLAGS.
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ARFLAGS, NMFLAGS, FPP, M4FLAGS, LIBS, FLIBS, FLDFLAGS | Miscellaneous | One or more of these may be needed for some platforms. Unless required, you should not set these environment variables, because that may interfere with the configure script.
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