Introduction to MATLAB

How to embed your standalone fortran/c code into matlab

• Change your main program into a subroutine, say, soussas_matlab.f
• Create an interface "gateway" subroutine which calls the main-program-turned subroutine, soussas_matlab.f

  #include < fintrf.h>  
  C Gateway function  
  C 
        SUBROUTINE MEXFUNCTION(NLHS, PLHS, NRHS, PRHS)
        
        POINTER PLHS(*), PRHS(*)        
        INTEGER NLHS, NRHS  
  C        
        POINTER MXCREATEFULL, MXGETPR        
        INTEGER MXGETM, MXGETN  
  C  
  C This is required for interfacing a .MEX file to MATLAB.  
  C        
        integer np        
        pointer pnp        
        real*8 rnp  
  C  
  C CHECK FOR PROPER NUMBER OF ARGUMENTS  
  C        
        IF (NRHS .NE. 1) THEN          
          CALL MEXERRMSGTXT('SOUSSA requires ONE input arguments')        
        ELSEIF (NLHS .NE. 0) THEN          
          CALL MEXERRMSGTXT('LU requires NO output argument')        
        ENDIF  
  C  
  C ASSIGN POINTERS TO THE VARIOUS PARAMETERS  
  C        
        pnp  = mxGetPR(PRHS(1))    !! get input array pointer via MATLAB fct
        
        call mxCopyPtrToReal8(pnp, rnp, 1)          
        
        np = int(rnp)    
        
  C CREATE MATRICES FOR RETURN ARGUMENTS    
  C DO THE ACTUAL COMPUTATIONS IN A SUBROUTINE    
        call soussas_matlab(np)           
        
        RETURN        
        END  

• Compile all subroutines, including the gateway routine, via the matlab "mex" compile script with appropriate switches

  # makefile for SOUSSA  
  SHELL=/bin/sh  
  .SUFFIXES:	.o .f .f90    
  
  FFLAGS = -64 -r10000 -mips4 -Ofast -OPT:roundoff=0    
  
  F77 = f77 $(FFLAGS)  
  F90 = f90 $(FFLAGS)  
  MEX = mex -I. FFLAGS='$$FFLAGS -64' LDFLAGS='$$LDFLAGS -64 -IPA' 
          FOPTIMFLAGS='-O3'
  
  ...      
  
  
  mex:   	
          $(MEX) $(SRC2) $(SRC7) $(SRC1) $(OBJ5)  	
          mv -f $(SRC2:.f=.mexsg64) soussas.mexsg64    ...  

• Optionally you can create an m-file that calls the newly created executable

  function soussas(np)  
  % function soussas(np)  
  %  
  %   runs the steady-state SOUSSA program EXTERNALLY via matlab  
  %   np -- number of processors  
  %  
  soussas_matlab(np)     % runs steady_state code to generate "matlab.out"

• Now proceed to use this m-file as you would any m-file
• All your I/O are through data files, not stdio
• Since there is no output coming back thru soussas_matlab.f, MATLAB does not have access to any output generated. You must read it in from a file.