问题
I'm compiling a C file (part of voc-release library) with Matlab and I'm getting the error below. I can't seem to solve it. Could anyone tell me what causes this error and what I can do about it?
mex -O features.cc
Writing library for features.mexw32
c:\users\safaa\appdata\local\temp\mex_ty~1\features.obj .text: undefined reference to '_round'
C:\PROGRA~1\MATLAB\R2009A\BIN\MEX.PL: Error: Link of 'features.mexw32' failed.
回答1:
If you had included more of the error message, I believe that this would have
already been answered, just an FYI. It looks like you're compiling a file
from some non-matlab source, which is fine, but you're likely going to have to
give more information about it. It appears that the features.cc file is
referencing a symbol round which is why you're getting the error. You'll need
to provide the library for the function, or compile it from source. If you do
a help mex, it should be able to give you information about the library linker
commands -L for the path and -l for the library. I seem to remember that
this feature doesn't work exactly as advertised, and requires you to use
-lC:/path/to/library/libfile.lib, or whatever. First of all, I would recommend
compiling the yprime example from the Matlab help. This will ensure that you
have your compiler setup correctly, which it sounds likel you do. Also, take a
look at the yprime.c file and the mexFunction. You may want to make sure the
compiler will accept a .cc file as a C file. It may interpret it as a C++
file which will cause you more headaches. You could rename the yprime.c file
to yprime.cc just to test the idea.
EDIT Thanks for providing the code. This should be cake my friend, complete cake. :-)
This is my error I get when I try to compile using:
Microsoft Visual C++ 2008 Express
>> mex -v -g features.c
This is mex, Copyright 1984-2007 The MathWorks, Inc.
-> Default options filename found in C:\Documents and Settings\wynkocl\Application\Data\MathWorks\MATLAB\R2009b
----------------------------------------------------------------
-> Options file = C:\Documents and Settings\wynkocl\Application Data\MathWorks\MATLAB\R2009b\mexopts.bat
MATLAB = C:\MATLAB\R2009B~1
-> COMPILER = cl
-> Compiler flags:
COMPFLAGS = /c /Zp8 /GR /W3 /EHs /D_CRT_SECURE_NO_DEPRECATE /D_SCL_SECURE_NO_DEPRECATE /D_SECURE_SCL=0 /DMATLAB_MEX_FILE /nologo /MD
OPTIMFLAGS = /O2 /Oy- /DNDEBUG
DEBUGFLAGS = /Z7
arguments =
Name switch = /Fo
-> Pre-linking commands =
-> LINKER = link
-> Link directives:
LINKFLAGS = /dll /export:mexFunction /LIBPATH:"C:\MATLAB\R2009B~1\extern\lib\win32\microsoft" libmx.lib libmex.lib libmat.lib /MACHINE:X86 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /incremental:NO /implib:"C:\DOCUME~1\WYNKOCL\LOCALS~1\TEMP\MEX_7L~1\templib.x" /MAP:"features.mexw32.map"
LINKDEBUGFLAGS = /DEBUG /PDB:"features.mexw32.pdb"
LINKFLAGSPOST =
Name directive = /out:"features.mexw32"
File link directive =
Lib. link directive =
Rsp file indicator = @
-> Resource Compiler = rc /fo "mexversion.res"
-> Resource Linker =
----------------------------------------------------------------
--> cl /c /Zp8 /GR /W3 /EHs /D_CRT_SECURE_NO_DEPRECATE /D_SCL_SECURE_NO_DEPRECATE /D_SECURE_SCL=0 /DMATLAB_MEX_FILE /nologo /MD /FoC:\DOCUME~1\WYNKOCL\LOCALS~1\TEMP\MEX_7L~1\features.obj -IC:\MATLAB\R2009B~1\extern\include -IC:\MATLAB\R2009B~1\simulink\include /Z7 -DMX_COMPAT_32 features.c
features.c
features.c(27) : error C2059: syntax error : 'type'
features.c(28) : error C2059: syntax error : 'type'
features.c(92) : warning C4013: 'round' undefined; assuming extern returning int
C:\MATLAB\R2009B~1\BIN\MEX.PL: Error: Compile of 'features.c' failed.
Ahhh...now we can find the issue. First, the C2059 error is do to the fact the the function max is being redefined, I'm pretty sure on that because that's how I fixed it. Then the round function has no prototype. Hmmm, that's odd. Well, that's because round is not in math.h so you'll need to implement one like at the top of your file like so:
int round(double number)
{
return (number >= 0) ? (int)(number + 0.5) : (int)(number - 0.5);
}
Now it compiles! As a tip, you can also try mex -v -g when you build to get more verbose debugging messages. Hope this gets you on your way!
Here's the last of what I've got here:
- Re-download voc-release4.01.tgz
- Extract and rename all
.ccfiles.cppfiles. Open the
compile.mscript and modify like so:mex -v -g resize.cpp mex -v -g dt.cpp mex -v -g features.cpp mex -v -g getdetections.cpp
% use one of the following depending on your setup % 0 is fastest, 3 is slowest
% 0) multithreaded convolution using SSE % mex -v -g fconvsse.cpp -o fconv
% 1) multithreaded convolution using blas % WARNING: the blas version does not work with matlab >= 2010b % and Intel CPUs % mex -O fconvblasMT.cpp -lmwblas -o fconv
% 2) mulththreaded convolution without blas % mex -O fconvMT.cpp -o fconv
% 3) convolution using blas mex -g -v fconvblas.cpp -LC:\MATLAB\R2009bSP1\extern\lib\win32\microsoft -lmwblas -output fconv
% 4) basic convolution, very compatible % mex -O fconv.cpp -o fconv
I recommend staying with option 3, pthreads is likely just a little too much for you at this point in time. :-)
- resize.cpp
Add #define bzero(b,len) (memset((b), '\0', (len)), (void) 0) int round(double number) { return (number >= 0) ? (int)(number + 0.5) : (int)(number - 0.5); } at the top and change:
alphainfo ofs[len];
to
alphainfo * ofs = (alphainfo *)mxMalloc(len);
and
assert(sy-1 >= 0);
to
assert(sy1 >= 0);
don't forget to mxFree(ofs); at the end of the function.
- dt.cpp: Change all
int32_ttoint32_T. features.cpp Add
int round(double number) { return (number >= 0) ? (int)(number + 0.5) : (int)(number - 0.5); }
- Make sure you have a directory
C:\MATLAB\R2009bSP1\extern\lib\win32\microsoft, if not put your Matlab release extern library directory there.
Enjoy.
来源：https://stackoverflow.com/questions/9602464/matlab-mex32-link-error-while-compiling-felzenszwalb-voc-on-windows