Matlab MEX Error: "mxCreateNumericArray" Static Type Issues

[danielRuckser]

Within MATLAB R2017b it is not possible to build the MEX files as explained. A quick successful workaround is at the end of this comment!

Used Hardware and Software: -> Mac Book Pro (Retina, 15inch, Mid 2014) -> macOS High Sierra, Version 10.13.1 -> Xcode Version 9.1 (9B55) -> MATLAB R2017b, Version 9.3.0.713579

I built the binaries with "cmake" as described in the reference.

Then the MATLAB MEX commands were as follows: 1) mex -setup C++ 2) cd /Applications/opengv/matlab 3) mex -I../include -I../third_party -I../third_party/eigen3 -L../build/lib -lopengv opengv.cpp

Output of MATLAB was:

Building with 'Xcode Clang++'. Error using mex /Applications/opengv/matlab/opengv.cpp:693:17: error: no matching function for call to 'mxCreateNumericArray_730' plhs[0] = mxCreateNumericArray(2, dims, mxDOUBLE_CLASS, mxREAL); ^~~~~~~~ /Applications/MATLAB_R2017b.app/extern/include/matrix.h:1131:30: note: expanded from macro 'mxCreateNumericArray'

define mxCreateNumericArray mxCreateNumericArray_730

                         ^~~~~~~~~~~~~~~~~~~~~~~~

/Applications/MATLAB_R2017b.app/extern/include/matrix.h:802:1: note: candidate function not viable: no known conversion from 'int [2]' to 'const size_t ' (aka 'const unsigned long ') for 2nd argument mxCreateNumericArray_730(size_t ndim, const size_t *dims, mxClassID classid, mxComplexity flag);

There were a lot of similar error messages like this one. Reason for this is the function "mxCreateNumericArray" that is called several times in "opengv.cpp" (that is located in opengv/matlab).

I assume an upward compatibility issue with more recent MATLAB versions like mine (R2017b). You can find the relevant MATLAB file in "MATLAB_R2017b.app/extern/include", it is named "matrix.h".

In this file the there are two relevant functions: mxCreateNumericArray_730(size_t ndim, const size_t *dims, mxClassID classid, mxComplexity flag) and mxCreateNumericArray_700(int ndim, const int *dims, mxClassID classid, mxComplexity flag).

Suitable pre-processor macros are also implemented in "matrix.h" to call "mxCreateNumericArray_730 " every time "mxCreateNumericArray" is called (without "_7xx" in the name). As easily seen these two functions have different input argument types. "int" & "const int" in the one case (which are signed types) and "size_t" & "const size_t" in the other case (which are unsigned types).

MATLAB is therefore unable to do a proper type conversion on its own. As a quick workaround in order to prevent you from changing many lines of code I recommend adding following line in the top of the file "opengv.cpp" (that is located in opengv/matlab): #define mxCreateNumericArray mxCreateNumericArray_700.

That will force MATLAB to use the (older) function "mxCreateNumericArray_700" with proper input argument types. After doing that everything seems to work fine.

[RobbyPee]

Thanks for this, it solved some build issues I was having as well.

I added the #define to the mex command:

mex -I../include -I../third_party -I../third_party/eigen3 -L../build/lib -lopengv opengv.cpp -DmxCreateNumericArray=mxCreateNumericArray_700

which saves having to modify any code (even if it's a minor modifcation)

[cristinabustos16]

I solved this compilation problem using this flag "mex -DMX_COMPAT_32 ..."

[zhaomoudou]

I solved this compilation problem using this flag "mex -DMX_COMPAT_32 ..."

It works for me. But when I run edgesDemo.m, I got an error: cannot find 'imPad' in edgesDetect.

[zhaomoudou]

I solved this compilation problem using this flag "mex -DMX_COMPAT_32 ..."

It works for me. But when I run edgesDemo.m, I got an error: cannot find 'imPad' in edgesDetect.

solved