MATLAB: Compiler Errors for a MEX file using the CPLEX C API

MATLABmex

I'm currently writing a MEX file that uses the CPLEX API in C to solve linear programming problems. Unfortunately, I run into a "symbol(s) not found for architecture x86_64" problem when I attempt to compile. I am including a verbose error report below.
Some more information:
– I can compile yprime.c – I am using MATLAB 2011b on Mac OSX 10.7.2 – I am compiling with GCC 4.2 included in XCode 4.2. – I already applied the XCode patch in (<http://www.mathworks.com/support/solutions/en/data/1-FR6LXJ/>)
I would greatly appreciate any advice you might have!
-> mexopts.sh sourced from directory (DIR = $PREF_DIR)
   FILE = /Users/berk/.matlab/R2011b/mexopts.sh
----------------------------------------------------------------
->    MATLAB                = /Applications/MATLAB_R2011b.app
->    CC                    = llvm-gcc-4.2
->    CC flags:
         CFLAGS             = -fno-common -no-cpp-precomp -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.5  -fexceptions -Wall
         CDEBUGFLAGS        = -g
         COPTIMFLAGS        = -O2 -DNDEBUG
         CLIBS              = -L/Applications/MATLAB_R2011b.app/bin/maci64 -lmx -lmex -lmat -lstdc++
         arguments          =  -DMX_COMPAT_32
->    CXX                   = llvm-g++-4.2
->    CXX flags:
         CXXFLAGS           = -fno-common -no-cpp-precomp -fexceptions -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.5
         CXXDEBUGFLAGS      = -g
         CXXOPTIMFLAGS      = -O2 -DNDEBUG
         CXXLIBS            = -L/Applications/MATLAB_R2011b.app/bin/maci64 -lmx -lmex -lmat -lstdc++
         arguments          =  -DMX_COMPAT_32
->    FC                    = gfortran
->    FC flags:
         FFLAGS             = -fexceptions -m64 -fbackslash
         FDEBUGFLAGS        = -g
         FOPTIMFLAGS        = -O
         FLIBS              = -L/Applications/MATLAB_R2011b.app/bin/maci64 -lmx -lmex -lmat -L -lgfortran -L -lgfortranbegin
         arguments          =  -DMX_COMPAT_32
->    LD                    = llvm-gcc-4.2
->    Link flags:
         LDFLAGS            = -Wl,-twolevel_namespace -undefined error -arch x86_64 -Wl,-syslibroot,/Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.5 -bundle -Wl,-exported_symbols_list,/Applications/MATLAB_R2011b.app/extern/lib/maci64/mexFunction.map
         LDDEBUGFLAGS       = -g
         LDOPTIMFLAGS       = -O
         LDEXTENSION        = .mexmaci64
         arguments          = 
->    LDCXX                 = 
->    Link flags:
         LDCXXFLAGS         = 
         LDCXXDEBUGFLAGS    = 
         LDCXXOPTIMFLAGS    = 
         LDCXXEXTENSION     = 
         arguments          = 
----------------------------------------------------------------
-> llvm-gcc-4.2 -c  -I/Users/berk/Applications/IBM/ILOG/CPLEX_Studio_Academic123/cplex/include/ilcplex/ -I/Applications/MATLAB_R2011b.app/extern/include -I/Applications/MATLAB_R2011b.app/simulink/include -DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.5  -fexceptions -Wall  -DMX_COMPAT_32 -O2 -DNDEBUG  "addcutsmx.c"
addcutsmx.c:488:4: warning: "/*" within comment
addcutsmx.c:37: warning: 'free_and_null' declared 'static' but never defined
addcutsmx.c:38: warning: 'usage' declared 'static' but never defined
-> llvm-gcc-4.2 -O -Wl,-twolevel_namespace -undefined error -arch x86_64 -Wl,-syslibroot,/Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.5 -bundle -Wl,-exported_symbols_list,/Applications/MATLAB_R2011b.app/extern/lib/maci64/mexFunction.map -o  "addcutsmx.mexmaci64"  addcutsmx.o  -L/Applications/MATLAB_R2011b.app/bin/maci64 -lmx -lmex -lmat -lstdc++
Undefined symbols for architecture x86_64:
  "_CPXLopenCPLEX", referenced from:
      _mexFunction in addcutsmx.o
  "_CPXLcreateprob", referenced from:
      _mexFunction in addcutsmx.o
  "_CPXLchgobjsen", referenced from:
      _mexFunction in addcutsmx.o
  "_CPXLnewcols", referenced from:
      _mexFunction in addcutsmx.o
  "_CPXLaddrows", referenced from:
      _mexFunction in addcutsmx.o
  "_CPXLlpopt", referenced from:
      _mexFunction in addcutsmx.o
  "_CPXLsolution", referenced from:
      _mexFunction in addcutsmx.o
  "_CPXLgetbase", referenced from:
      _mexFunction in addcutsmx.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
      mex: link of ' "addcutsmx.mexmaci64"' failed.
Error using mex (line 206)
Unable to complete successfully.

Best Answer

It looks like MEX can't find the CPLEX libraries. Try adding:
 -L<path/to/cplex/libs> -l<name_of_library>
when you invoke MEX.
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