compile c++ code using mex

Hi, I want to compile my c++ code using mex. The error information is as follows. My friend compiled it successfully using his matlab and computer. So I am wondering what my problem is.

In Matlab command window:

>> mex main.cpp -o test Undefined symbols: "_mexFunction", referenced from: -exported_symbol[s_list] command line option ld: symbol(s) not found collect2: ld returned 1 exit status

    mex: link of ' "test.mexmaci64"' failed.

Error using mex (line 206) Unable to complete successfully. >>

My computer: Mac OS X 10.6.8

Xcode: Version 3.2.6

Matlab: R2012a

My c++ code:

#include iostream

int main (int argc, char * const argv[]) { // insert code here... std::cout << "Hello, World!\n"; return 0; }

Thanks.

Answer 1

[Jan]

Your code does not have a the required gateway function mexFunction. So you can compile it from the shell or in the IDE of your compiler, but it is not useful and valid for a compiled MEX function.

You can find tutorials for creating and using MEX files e.g. at http://www.mathworks.com/help/matlab/create-mex-files.html.

Answer 2

[Zhenjia]

I used -v -g to output more compiling information. It looks my error is related to 64 bit Mac system. I am still looking for answers to solve this problem. Thanks.

mex -v -g -largeArrayDims main.cpp

************************************************************************ Warning: Neither -compatibleArrayDims nor -largeArrayDims is selected. Using -compatibleArrayDims. In the future, MATLAB will require the use of -largeArrayDims and remove the -compatibleArrayDims option. For more information, see: http://www.mathworks.com/help/techdoc/matlab_external/bsflnue-1.html ************************************************************************

-> mexopts.sh sourced from directory (DIR = $PREF_DIR) FILE = /Users/zhenjia/.matlab/R2012a/mexopts.sh ---------------------------------------------------------------- -> MATLAB = /Applications/MATLAB_R2012a.app -> CC = 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 CDEBUGFLAGS = -g COPTIMFLAGS = -O2 -DNDEBUG CLIBS = -L/Applications/MATLAB_R2012a.app/bin/maci64 -lmx -lmex -lmat -lstdc++ arguments = -> CXX = 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_R2012a.app/bin/maci64 -lmx -lmex -lmat -lstdc++ arguments = -> FC = gfortran -> FC flags: FFLAGS = -fexceptions -m64 -fbackslash FDEBUGFLAGS = -g FOPTIMFLAGS = -O FLIBS = -L/Applications/MATLAB_R2012a.app/bin/maci64 -lmx -lmex -lmat -L -lgfortran -L -lgfortranbegin arguments = -> LD = 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_R2012a.app/extern/lib/maci64/mexFunction.map LDDEBUGFLAGS = -g LDOPTIMFLAGS = -O LDEXTENSION = .mexmaci64 arguments = -> LDCXX = -> Link flags: LDCXXFLAGS = LDCXXDEBUGFLAGS = LDCXXOPTIMFLAGS = LDCXXEXTENSION = arguments = ----------------------------------------------------------------

-> g++-4.2 -c -I/Applications/MATLAB_R2012a.app/extern/include -I/Applications/MATLAB_R2012a.app/simulink/include -DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -fexceptions -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.5 -g "main.cpp"

-> gcc-4.2 -g -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_R2012a.app/extern/lib/maci64/mexFunction.map -o "main.mexmaci64" main.o -L/Applications/MATLAB_R2012a.app/bin/maci64 -lmx -lmex -lmat -lstdc++

Undefined symbols: "_mexFunction", referenced from: -exported_symbol[s_list] command line option ld: symbol(s) not found collect2: ld returned 1 exit status

    mex: link of ' "main.mexmaci64"' failed.

Answer 3

[Zhenjia]

Thanks. I compiled the example on the Matlab website successfully. Should I write the mexFunction for each c++ code? My c++ code can be compiled successfully in Linux system without writing any mexFunction. I am wondering whether my Matlab in Mac has missed some thing when I installed it. Is there any good tutorial about writing a mexFuction? Thanks.