MATLAB: Errors in linking fortran code that opens a MAT-file

.mat filefortran

I have to open a MAT-file using fortran. I followed the example file but I am facing some problems while linking. The compiling happens fine.
Minimal code:
#include "fintrf.f90"
PROGRAM main 
USE ssa
USE dmotifs
USE param
IMPLICIT NONE
! MAT-FILE Declarations !
INTEGER matOpen, matGetDir !, matGetNextVariable
INTEGER matGetVariableInfo
INTEGER mp, dir, adir(100), pa
INTEGER mxGetM, mxGetN, matClose
INTEGER ndir, i, clstat
CHARACTER*32 names(100) !, name
!===========================!
if(all(fnames(:)%fn .NE. argfun)) then
    write(*,*) "No such motif: ",argfun
    write(*,*) "Input format-> main <motifname>"
    stop
else
    fin=fchton(argfun)  
    y0=nM2m*analys(p,argfun)
    ! ==> OPEN MAT-file <== !
    mp=matOpen('./PRMS_lxr_29Apr15.mat','r')
    if (mp .eq. 0) then
         write(6,*) "Can't open MAT-file"
         stop
    end if
    dir = matgetdir(mp, ndir)
      if (dir .eq. 0) then
         write(6,*) "Can't read MAT-file-directory."
         stop
    endif
    call mxCopyPtrToPtrArray(dir, adir, ndir)
    do 20 i=1,ndir
         call mxCopyPtrToCharacter(adir(i), names(i), 32)
 20 continue
    write(6,*) 'Directory of Mat-file:'
    do 30 i=1,ndir
        write(6,*) names(i)
 30 continue
    write(6,*) 'Getting Header info from first array.'
    pa = matGetVariableInfo(mp, names(1))
    write(6,*) 'Retrieved ', names(1)
    write(6,*) '  With size ', mxGetM(pa), '-by-', mxGetN(pa)
    call mxDestroyArray(pa)
    clstat=matClose(mp)
  call gillespie(fmotifs(fin),y0,p,tf,opt,t,y)
end if
END PROGRAM main
I am using gfortran 4.8.3 for compiling using the default command:
gfortran main.f90 dmotifs.o param.o ssa.o -o main
This code compiles fine when I do not include:" #include "finitrf.h" ", otherwise the compiler says
Warning: main.f90:1: Illegal preprocessor directive
I tried renaming finitrf.h to finitrf.f90 but it did not make any difference. Nonetheless during linking I am getting these errors:
main.f90:(.text+0x3ea): undefined reference to `matopen_'
main.f90:(.text+0x487): undefined reference to `matgetdir_'
main.f90:(.text+0x52b): undefined reference to `mxcopyptrtoptrarray_'
main.f90:(.text+0x583): undefined reference to `mxcopyptrtocharacter_'
main.f90:(.text+0x71b): undefined reference to `matgetvariableinfo_'
main.f90:(.text+0x804): undefined reference to `mxgetm_'
main.f90:(.text+0x855): undefined reference to `mxgetn_'
main.f90:(.text+0x89c): undefined reference to `mxdestroyarray_'
main.f90:(.text+0x8b0): undefined reference to `matclose_'
collect2: error: ld returned 1 exit status
Do I need a makefile or add additional arguments in the compile command.

Best Answer

The compiler requires -cpp option for the pre-processor to recognize the header file and not to treat it as illegal.
Linking requires finitrf.h , which is usually located in the matlabroot/extern/include and the essential libraries are present in matlabroot/bin/<arch>.
But just specifying this does not work and specification of the exact matlab library seems essential; these are libmat.so and libmx.so
These libraries are in turn dependent on other libraries so another flag is required to set the rpath.
Finally it works with following command:
gfortran main.f90 dmotifs.o param.o ssa.o -I/usr/local/matlab2008a/extern/include -L/usr/local/matlab2008a/bin/glnxa64 -cpp -o main -lmat -lmx -Wl,-rpath /usr/local/matlab2008a/bin/glnxa64/
or in general
gfortran program.f90 -I<matlabroot>/extern/include -L<matlabroot>/bin/<arch> -cpp -lmat -lmx -Wl, -rpath <matlabroot>/bin/<arch> -o program.out
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