Hi!

I received a code from github (https://github.com/exafmm/exafmm-alpha). I wish to incorporate the part of the code in our in-house fortran code.

The code from github is:

    program main
      implicit none
      integer i,ni,nj,images
      integer,dimension (128) :: iseed
      real(8) diff,norm
      real(8),parameter :: pi=3.14159265358979312d0
      real(8),allocatable,dimension(:) :: xi,ui,ud,xj,gj
      ni = 1000 !10000
      nj = 1000 !500000
      allocate( xi(3*ni),ui(3*ni),ud(3*ni),xj(3*nj),gj(3*nj) )
      do i = 1,128
         iseed(i) = 0
      enddo
      call random_seed(put=iseed)
      call random_number(xi)
      call random_number(xj)
      call random_number(gj)
      do i = 1,nj
         xj(3*i-2) = 5*(xj(3*i-2) - 0.5) * pi
         xj(3*i-1) = 5*(xj(3*i-1) - 0.5) * pi
         xj(3*i-0) = 5*(xj(3*i-0) - 0.5) * pi
         gj(3*i-2) = (gj(3*i-2) - 0.5) / ni
         gj(3*i-1) = (gj(3*i-1) - 0.5) / ni
         gj(3*i-0) = (gj(3*i-0) - 0.5) / ni
      enddo
      do i = 1,ni
         xi(3*i-2) = 3*(xi(3*i-2) - 0.5) * pi
         xi(3*i-1) = 3*(xi(3*i-1) - 0.5) * pi
         xi(3*i-0) = 3*(xi(3*i-0) - 0.5) * pi
         ui(3*i-2) = 0
         ui(3*i-1) = 0
         ui(3*i-0) = 0
      enddo
      images = 0
      call fmm_init(images)
      call fmm_biot_savart(ni,xi,ui,nj,xj,gj)
      call fmm_finalize()
      deallocate( xi,ui,ud,xj,gj )
    end program main
And the make file for this is:

    include ../Makefile.include
    lib_serial_ij: serial_wrapper_ij.o $(OBJECT)
        ar -cr libfmm.a serial_wrapper_ij.o $(OBJECT)
        ranlib libfmm.a

    test_serial_ij: test_serial_ij.o
        make lib_serial_ij
        $(FC) $? -L. -lfmm $(LFLAGS)
        ./a.out

And Makefile.include is:

    .SUFFIXES: .cxx .cu .f90 .o
    .PHONY: docs

    CUDA_INSTALL_PATH = /usr/local/cuda

    DEVICE  = cpu
    #~ DEVICE  = gpu

    CXX     = mpicxx -g -O3 -lstdc++ -fPIC -fopenmp -ffast-math -funroll-loops -rdynamic -Wfatal-errors -I../include
    NVCC    = nvcc -Xcompiler "-fopenmp -O3" -lstdc++ -use_fast_math -I../include
    FC      = mpif90 -g -O3 -fPIC -fopenmp -funroll-loops -rdynamic -I../include
    FCC      = mpif90 -c -O3 -fPIC -fopenmp -funroll-loops -rdynamic -I../include
    LFLAGS  = -D$(DEVICE) -lstdc++ -ldl -lm
    LFLAGS  += -lmpi_cxx
    LFLAGS  += -lpthread

    ifeq ($(DEVICE),gpu)
    LFLAGS  += -lcudart
    endif
    OBJECT  = ../kernel/$(DEVICE)Laplace.o ../kernel/$(DEVICE)BiotSavart.o\
        ../kernel/$(DEVICE)Stretching.o ../kernel/$(DEVICE)Gaussian.o\
        ../kernel/$(DEVICE)CoulombVdW.o

    .cxx.o:
        $(CXX) -c $? -o $@ $(LFLAGS)
    .cu.o:
        $(NVCC) -c $? -o $@ $(LFLAGS)
    .f90.o:
        $(FC) -c $? -o $@

Now I wish to change the code a bit, instead of the main program I wish it as subroutine so that I can call it in our in-house code. The name of the subroutine is FMM_ij looks like:

    subroutine FMM_ij (n_s,n_t,v_x,v_y,v_z,xi,ui,xj,gj)
    !###########################!
    integer, intent (in) :: n_s, n_t
    real*8, intent (out) :: v_x(n_t)
    real*8, intent (out) :: v_y(n_t)
    real*8, intent (out) :: v_z(n_t)
    real*8, intent (in) :: xi(3*n_t)
    real*8, intent (in) :: ui(3*n_t)
    real*8, intent (in) :: xj(3*n_s)
    real*8, intent (in) :: gj(3*n_s)
    !###########################!
    integer i,images
    real(8),parameter :: pi=3.14159265358979312d0
    !###########################!

    images = 0
    print*, n_t,n_s,size(xi),size(ui),size(xj),size(gj)
    print*, xi(500),ui(500),xj(500),gj(500)
    call fmm_init(images)
    call fmm_biot_savart(n_t,xi,ui,n_s,xj,gj)

    do i = 1,n_t
        v_x(i) = ui(3*i-2)
        v_y(i) = ui(3*i-1)
        v_z(i) = ui(3*i-0)
    enddo

    call fmm_finalize()
    end subroutine FMM_ij
What changes I should do in Makefile so that I get an object file of the subroutine FMM_ij and can call this subroutine in any other program?
Thanks a lot.