[SOLVED] Fortran unable to call external library

Fortran unable to call external library

I am trying to use an external library called "decomp_2d" with my fortran program. I have an environment variable declared "DECOMP2D" which points to the directory where "decomp_2d" is located. This directory has the following structure:

[k00603@fe01p03 2decomp_fft]$ls
doc  examples  include  lib  Makefile  README  src
[k00603@fe01p03 2decomp_fft]$ls lib/
lib2decomp_fft.a  Makefile
[k00603@fe01p03 2decomp_fft]$ls include/
decomp_2d_fft.mod  decomp_2d_io.mod  decomp_2d.mod  glassman.mod

In another directory I am trying to call a program which uses the subroutines of this library. But when I am doing this, I am getting a compile time error. I am attaching a minimal fortran code which I am using and the Makefile I am using to compile. It is a Fujitsu machine and they have there own fortran compiler which I am using to compile:

The program:

  program   Sora_v71

! Use the external library
  use decomp_2d

  integer n

  call decomp_2d_init(n,n,n,n,n)

  stop
  end

Makefile:

# Lines included for using the 2decomp libraries
INC_2DECOMP = -I$(DECOMP2D)/include/
L2DECOMP = -L$(DECOMP2D)/lib/ -l2decomp_fft

## ------------------------------------------------------
RM        =  rm
SRCDIR    = .
LIBDIR    = .
BIN       = binary
OBJS      = main.o 

## -------------------------------------------------------
mpifrtpx=$(shell which mpifrtpx)
FC=$(mpifrtpx)

FFLAGS   = $(F90FLAG) $(INC_2DECOMP) 
LFLAGS   = $(F90FLAG) -L$(LIBDIR) $(L2DECOMP)

## -------------------------------------------------------
all: $(BIN)

$(BIN): $(OBJS)
    @echo Linking $(BIN) .....
    $(FC) $(LFLAGS) -o $@ $(OBJS)

.f.o:
@echo Compiling $*.f
$(FC) $(FFLAGS) -c $(SRCDIR)/$*.f

clean:
@echo 'Cleaning .....'
$(RM) -f core *.o *~ *.L *.O $(BIN) $(SIZE_FILE)

When I am typing "make" I am getting the following error:

[k00603@fe01p04 test]$make
Compiling main.f
/opt/FJSVtclang/GM-1.2.0-11/bin/mpifrtpx  -I/home/hp120242/k00603/2decomp_fft//include/ -c ./main.f
Linking binary .....
/opt/FJSVtclang/GM-1.2.0-11/bin/mpifrtpx  -L. -L/home/hp120242/k00603/2decomp_fft//lib/ -l2decomp_fft -o binary main.o 
main.o: In function `MAIN__':
main.f:(.text+0x4c): undefined reference to `decomp_2d.decomp_2d_init_'
main.o:(.data+0x0): undefined reference to `decomp_2d.decomp_2d_init_'
make: *** [binary] Error 1

Any ideas?

Solution

With some linkers the order of the libraries in the linking command matters. Generally they have to come after the object files that reference them. Try to switch $(LFLAGS) and $(OBJS) in the link command.