call Fortran subroutine from Mathematica // use NETLink and DLL

*To*: mathgroup at smc.vnet.net*Subject*: [mg120450] call Fortran subroutine from Mathematica // use NETLink and DLL*From*: "Scot T. Martin" <smartin at seas.harvard.edu>*Date*: Sat, 23 Jul 2011 02:29:20 -0400 (EDT)

This post explains how to call a Fortran subroutine as a DLL from Mathematica. I don't think the hints in this post exist in explicit form in the Wolfram documentation or in the MathArchive, at least so far as I could find. There is information in a post from Wolfram for how to use Mathlink via C wrappers to get to Fortran subroutines (version 3 of Mathematica? http://library.wolfram.com/infocenter/TechNotes/174/). *BUT* I think since the introduction of NETLink into Mathematica (version 6?), the matter is now much more straightforward, at least in a Windows environment. The purpose of this post is therefore to a future user who might want to follow what I have done. >From Windows7, 64-bit, and using the gnu compiler (http://gcc.gnu.org/wiki/GFortranUsage), here is the trace of the CMD commands: C:\Demo>dir 22-Jul-11 21:16 336 SumAndDifference.f90 C:\Demo>more SumAndDifference.f90 subroutine sum_and_difference(i,j,resultArray) implicit none integer*4, intent (in) :: i integer*4, intent (in) :: j integer*4, dimension(2), intent (out) :: resultArray resultArray(1) = i + j resultArray(2) = i - j return end subroutine sum_and_difference C:\Demo>gfortran -c SumAndDifference.f90 C:\Demo>gfortran -s -shared -mrtd -o SumAndDifference.dll SumAndDifference. o C:\Demo>dir 22-Jul-11 21:21 12,800 SumAndDifference.dll 22-Jul-11 21:16 336 SumAndDifference.f90 22-Jul-11 21:20 429 SumAndDifference.o Now follows the Mathematica part: In[1]:= Needs["NETLink`"] In[2]:= SetDirectory@NotebookDirectory[] Out[2]= "C:\\MyFortran" In[3]:= $pathToDLL = FileNameJoin[{Directory[], "SumAndDifference.dll"}] Out[3]= "C:\\MyFortran\\SumAndDifference.dll" [To understand below, read: http://www.wolfram.com/learningcenter/tutorialcollection/NETLinkUserGuide/ ] [Note addition of "_" to "sum_and_difference" that is done by compiler.] In[4]:= SumAndDifference = DefineDLLFunction["sum_and_difference_", $pathToDLL, "void", {"Int32*", "Int32*", "Int32[]"}] In[5]:= results = MakeNETObject[{0, 0}, "System.Int32[]"] In[6]:= SumAndDifference[10, 20, results] In[7]:= NETObjectToExpression@results Out[7]= {30, -10}