Linking FFTW into Matlab Mex file - windows

I am trying to run FFTW code in a mex file. This is strictly for the purpose of development and testing. After some googling, I see that others have tried to do something similar and have had related problems, but I have not found any solutions. When attempting to run the mex file, Matlab tells me:
??? Error using ==>
chirpTransform.mxCta Invalid MEX-file
'\removed\my\directory\+chirpTransform\mxCta.mexw32':
The specified procedure could not be
found.
.
I am using gnumex with MinGW to build the mex file because LCC seems to have some issues. I have tried using the 32 bit DLL from the FFTW site (http://www.fftw.org/install/windows.html). I have tried using the fftwf3.dll in the Matlab 2009b bin directory. I built the dll from source using Msys/MinGW. In all cases, the results are the same. In all cases I did the following to generate the lib file.
c:\gnumex\mexdlltool.exe -d
libfftw3f-3.def -D libfftw3f-3.dll -l
libfftw3f.lib --as C:\MinGW\bin\as.exe
I also tried using the visual studio lib.exe tool and experimented with various mexdlltool flags.
It appears that I can directly call functions in the fftwf3-3.dll using Matlab's loadlibrary functionality. Since the DLL appears not to be the problem, I tried building a static version of fftwf3 and linking it directly into the mex file. I got the same results! If I remove the FFTW code, the mex file runs fine. I have just about given up at this point, and I am tyring to come up with alternative methods of testing.

I've run into this issue with other mex functions. In my experience, it typically means that there is a dependency issue. Some dependency is not located.
Here is a link to TMW's documentation on this issue:
Invalid MEX-File Error
Give it a read, and then try using dependency walker to diagnose the problem.

It's been a long time, and my setup has changed, but this works for me now. I suspect hoogamaphone was right. I probably didn't have the fftw dll in the same directory as the mex dll (and it wasn't in my path). In fact, 64 bit Matlab 2016a still gives you a warning about not being able to find the mex file when, in fact, it's a dependency that's missing.
My current setup is using the Visual Studio 2013 C++ compiler by default. As mentioned on the fftw web site, you need to generate a lib file for linking. You can run the Visual Studio command prompt from a regular command prompt like so:
"%VS120COMNTOOLS%VsDevCmd.bat"
Then run the following in the directory with the def file.
lib /machine:x64 /def:libfftw3f-3.def
And compile.
mex mxCta.c cta.c -I../fftw -L../fftw -llibfftw3f-3.lib
Perhaps another possibility is that gnumex introduced some dependency into the mex dll. I no longer recall whether I had used gnumex successfully testing other code. When using cygwin, if you don't use the mingw compiler (x86_64-w64-mingw32-gcc), you'll end up with a dependency on the cygwin1.dll.
Finally, if you use more than one compiler, make sure all the compiler flags are the same (same function calling conventions, ABI, etc). Also, Mathworks has changed the mex build procedure. In a recent project, I copied mexconfig.xml to my local directory from
C:\Users\myuser\AppData\Roaming\MathWorks\MATLAB\R2016a\mex_C_win64.xml
and edited the compiler flags like so:
COMPFLAGS="/Zp8 /GR /W3 /EHs /nologo /MD /Gz /TC"
If you use a custom build file, use the -f option.
mex mxCustom.c custom.lib -f mexconfig.xml

Related

MATLAB mex not looking for compiler gfortran on macOS

I need to call some Fortran code from within MATLAB. I did some research and read about the mex command and how to use it. Sadly I'm already failing at getting the Fortran compiler to work.
First of all, here's my setup:
macOS Sierra 10.12.1 (latest version)
MATLAB R2016b (latest version)
gfortran 4.9.2 (installed via .dmg from official GNU site)
According to the MATLAB documentation, I can use mex -setup FORTRAN to prepare mex for building a mex-file from Fortran. However, running the command in verbose mode yields the following output: mex -setup -v FORTRAN
Verbose mode is on.
... Looking for compiler 'Intel Fortran Composer XE' ...
... Looking for environment variable 'IFORT_COMPILER16' ...No.
... Looking for environment variable 'IFORT_COMPILER15' ...No.
... Looking for environment variable 'IFORT_COMPILER14' ...No.
... Looking for environment variable 'IFORT_COMPILER13' ...No.
... Executing command 'which ifort' ...No.
Did not find installed compiler 'Intel Fortran Composer XE'.
Error using mex
No supported compiler or SDK was found. For options, visit
http://www.mathworks.com/support/compilers/R2016b/maci64.html.
Following the link, one can see that MATLAB does support GNU gfortran 4.9.x on Linux. On Mac however, only Intel's commercial compilers are listed as supported. That's what mex seems to be looking for as well.
Since Mac can also use gfortran to compile Fortran code I thought it'd be possible to get it to work with MATLAB. I've also googled alot and found questions like this one on the MathWorks forum, which suggests that MATLAB should be able to use gfortran, even on Mac.
That's what I think is strange, my MATLAB isn't even looking for a gfortran compiler. All it does is look for an Intel compiler, can't find one and then throws above stated error message.
Regarding my gfortran installation. It is definitely 4.9.2 (which is listed as supported under Linux), which gfortran returns /usr/local/bin and I can successfully compile programs via Terminal.
By the way, mex -setup ANY successfully lists the compilers for C and C++ but no Fortran.
MEX configured to use 'Xcode with Clang' for C language compilation.
Warning: The MATLAB C and Fortran API has changed to support MATLAB
variables with more than 2^32-1 elements. In the near future
you will be required to update your code to utilize the
new API. You can find more information about this at:
http://www.mathworks.com/help/matlab/matlab_external/upgrading-mex-files-to-use-64-bit-api.html.
MEX configured to use 'Xcode Clang++' for C++ language compilation.
Warning: The MATLAB C and Fortran API has changed to support MATLAB
variables with more than 2^32-1 elements. In the near future
you will be required to update your code to utilize the
new API. You can find more information about this at:
http://www.mathworks.com/help/matlab/matlab_external/upgrading-mex-files-to-use-64-bit-api.html.
To choose a different C compiler, select one from the following:
Xcode with Clang mex -setup:'/Users/Lennart/Library/Application Support/MathWorks/MATLAB/R2016b/mex_C_maci64.xml' C
Xcode Clang++ mex -setup:'/Users/Lennart/Library/Application Support/MathWorks/MATLAB/R2016b/mex_C++_maci64.xml'
I also had a look at those .xml files mentioned at the very end of the last output. There was no file for anything having to do with Fortran and I wasn't able to successfully write one myself. I'm not even sure whether that's the problem...
So simply put my question is: How can I get MATLAB to actually look for and then of course also find my gfortran compiler to use it to compile mex files?
Appreciate your help!
Thanks to hsuyaa and the provided link I was able to resolve my problem. As it needed some more experimenting by myself, I'd like to post how exactly I was able to get gfortran to work.
Look at this link and the accepted answer. Although the MathWorks Team explicitly states that the instructions are specifically written for xCode 7.0 and MATLAB R2015b, I got everything to work with xCode 8.1, MATLAB R2016b and macOS Sierra 10.12.
MATLAB seems to be storing the compiler configuration details in .xml-files as mentioned before. You can find the directory in MATLAB by entering
cd( fullfile( matlabroot, 'bin', 'maci64', 'mexopts' ) );
I did perform a fresh install of MATLAB before but at that location, only three files where located, one for Clang, one for Clang++, one for Intel's Fortran. The gfortran one was simply missing.
The solution author at MathWorks appended all of these .xml-files to his post. I downloaded the files and copied gfortran.xml to the above mentioned folder. This granted partial success in that it made MATLAB actually look for gfortran when running the mex setup.
However, since the files are not up-to-date, I had to add a few lines. I don't exactly understand how the configuration files work, but I noticed that some lines where referring to older macOS versions. Download the file gfortran.xml behind the above link and then add the following:
Wherever you see
<dirExists name="$$/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk" />
or
<cmdReturns name="find $$ -name MacOSX10.11.sdk" />
also add
<dirExists name="$$/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk" />
or
<cmdReturns name="find $$ -name MacOSX10.12.sdk" />
macOS 10.12 is Sierra. Saving the file and running mex -setup FORTRAN again successfully identified gfortran and set it as the fortran compiler for mex.
Your matlab version is not able to detect the supported compilers. May be this Link can help.

Error: multiple definition of `fprint' - while using SDL_ttf

I have a custom library that utilises this code (https://www.dropbox.com/s/iwft7snjmntf160/SoASpriteFont.zip?dl=0).
The linked code was written for Visual Studio; I am using CodeLite on Windows.
Its has a SpriteFont.cpp that uses fprintf.
The static library that has SpriteFont as part of it compiles fine on its own and produces a *.a quite happily.
However when I use SpriteFont via other code, I get a linker error (if I am not mistaken):
D:/Coding/TDM-GCC-32/bin/g++.exe -o ./Debug/tmp #"tmp.txt" -L. -L../deps/lib/ -L../bengine/lib/ -lbengine -lSDL2_ttf -lSDL2main -lSDL2 -lopengl32 -lglew32
D:/Coding/TDM-GCC-32/bin/../lib/gcc/mingw32/5.1.0/../../../libmsvcrt.a(dsnos00619.o):(.text+0x0): multiple definition of `fprintf'
../bengine/lib//libbengine.a(SpriteFont.cpp.o):D:/Coding/TDM-GCC-32/include/stdio.h:243: first defined here
I have read all over and found some similar situations but nothing that I have managed to use to resolve this.
It sounds like there is an issue with the way TDM-GCC redefines fprint in its' stdio.h, but I can't see how. Upon further examination, I believe the problem may lie with SDL_ttf, which is used by SpriteFont.
Also, I have tried using other functions from stdio.h and they compile fine; problem only seems to be fprintf
I have tried to create a barebones program to illustrate the problem. Hope it helps. Hopefully the fact it is a CodeLite project won't be a source of irritation.
If I can provide more info or code please ask.
This usually happens in MinGW when linking against a dll file that also has file in the form of <NAME>.dll.a
To fix this, just link against the dll directly (I recently encountered the same problem when build LLDB debugger on Windows /w MinGW, the solution was to link directly against the dll file and delete the dll.a file

Another GSL linking error in Windows

I've done everything, and it's payed off.
Trying to compile a mex file from MATLAB using the Windows 7.1 SDK.
~ I've created an compiled my C source code on GCC
~ I've created a MEX file that links and compiles fine via GCC on both Linux and OS X. Does not crash MATLAB, gateway function works fine
~ After much confusion, I switched my dev platform form 64-bit to x86 Win7
~ I've found .dll built files, but they do not link. Linking libs in MATLAB using MATLAB's linker flags will default to .lib, so...
~ I've found--after much googling--simple, pre-compiled x86 GSL .lib's and source files and linked them with MATLAB, eliminating any gsl_blas.h-and-it's-dependencies unrecognized external symbol errors
~ I've re-written every single variable declaration in my source code such that it is C89 standard compatible
~ I've set linker flags appropriately to avoid LIBCMT and any other LIB conflicts
~ I've installed the 2010 and 2012 VC C Runtime libraries
~ I've checked to make sure I have msvcrt.dll and msvcp60.dll in my System files
~ I've followed multiple tutorials online on how supposedly link everything together, most of which had nothing broken links or un-replicable results. I didn't find much to go off of for Cygwin or MinGW.
~ I've tried using the Lcc-win32 2.4.1 compiler
If I was doing basic matrix and vector operations, I'd be set, but unfortunately the various decomposition routines I'm utilizing require parts from the cblas library, which I linked as well, but I get ~30 errors all reporting the same thing...
cblas.lib(ctrsv.obj) : error LNK2001: unresolved external symbol __libm_sse2_sqrt_precise
Here's my MATLAB command.
mex -largeArrayDims -IC:\gsl\include -LC:\gsl\lib -lgsl -lcblas LINKFLAGS="$LINKFLAGS /NODEFAULTLIB:libcmt.lib" file1.c file2.c
So, out of options and frustrated out of my mind, I (naturally) come to stack overflow. Anyone have any idea how to solve this one? The only thing I've foudn on google points to wineHQ errors, not very helpful.
And, if possible, I'd rather not try to compile first on VS201X. I have access to whatever version I need, if necessary, but to me that just seems like a redundant step. Maybe I'm spoiled with Unix-based file system management and linking, though.
It's easy to compile the GSL library under MinGW, in fact the process of compiling from sources is exactly identical to that in Linux. Here are the steps I took:
Setup MinGW for Windows. I am using MinGW-w64 but there is also the popular TDM-GCC distribution which comes with a friendly web-installer.
Obtain GSL sources, and extract the tarball (gsl-1.16.tar.gz is the latest as of now)
Compile as usual, I've used the following commands:
$ ./configure --host=x86_64-w64-mingw32 --prefix=/mingw/local --enable-shared --enable-static
$ make
$ make install
It should take several minutes to finish. Maybe you can enable parallel builds to speed up compilation (make -j)
You'll end up with the necessary files installed in /mingw/local with the usual structure underneath (bin, lib, include).
Finally you can compile an example program with:
$ export PATH=/mingw/local:$PATH
$ gcc `gsl-config --cflags` -o main main.c `gsl-config --libs`
Of course if you prefer using Visual C++ as compiler, people out there have prepared solutions to build GSL using Visual Studio (either manually created project files, or using a build system like CMake and the like). See this question for such projects.
A third option is using Cygwin.

Error in CodeBlocks C++ program and how to set default main class

I have included the boost library in a Codeblocks c++ project.
Now, in the file
boost/function.hpp
there is an include statement
#include <boost/preprocessor/iterate.hpp>
However I get this error in Codeblocks when I try and compile:
/home/arvind/Documents/Workspace/Browser/boost/function.hpp|15|fatal error:
boost/preprocessor/iterate.hpp: No such file or directory|
What am I doing wrong here? I have simply included the Boost library as it is.
Also, I cannot find the screen/option to set the main class (which will actually execute).
How do I do this?(I am new to CodeBlocks hence this question).
Your boost includes seem to be in a non-standard/system directory : /home/arvind/Documents/Workspace/Browser, you must tell the compiler to look there (gcc -I command-line switch).
Go to Project->Build Options->Search Directories->Compiler and add the directory where boost includes are. I don't have a codeblocks install right here so this was from here.
If you can, I would recommand installing boost on your system once and for all instead of just copying files in your codeblocks workspace.

Linking APR (Apache Portable Runtime) with CMake in Windows

i would like to compile a project using the apache portable runtime libraries (APR) and cmake. It all looks good when running along with linux (as there i can use the apr-1-config shell script). Nevertheless, in windows it looks like cmake does not bind or link the included files correctly. I've tried some different methods, like importing the libapr-1.lib as static library or just target_link_library all stuff, yet nothing seems to work. I always get the
error LNK2019: unresolved external symbol
linker errors when compiling using visual studio. It does not matter which function i am calling, as an example i am calling apt_pool_create, as it does not require any parameters.
I am still wondering as visual studio is finding the files with IntelliSense and showing me all documentations inline. Also the compiler does not fail to build when an apt_pool* pointer object is defined and initialized with NULL.
Maybe anyone does know why there are these linker problems. Following are some snippets out of the CMakeLists.txt files:
CMakeLists.txt (partial)
# Include unimrcp requirements (apr package)
IF(WIN32) # Search APR in windows
INCLUDE(${PROJECT_SOURCE_DIR}/cmake_modules/FindAPR_windows.cmake)
ELSE(WIN32) # Search APR in unix
INCLUDE(${PROJECT_SOURCE_DIR}/cmake_modules/FindAPR_unix.cmake)
ENDIF(WIN32)
# Set link libraries
SET(TARGET_LINK_LIBS
${APR_LIBRARIES}
${APRUTIL_LIBRARIES}
${PTHREADS}
)
SET(CLIENT_SOURCES ...)
SET(CLIENT_HEADERS ...)
# Include intermediary files
INCLUDE_DIRECTORIES(
${CMAKE_CURRENT_BINARY_DIR}
${APR_INCLUDE_DIR}
${APRUTIL_INCLUDE_DIR}
)
# Add executable and link libraries
ADD_EXECUTABLE(${CLIENT_TARGET} src/main.cpp ${CLIENT_SOURCES} ${CLIENT_HEADERS})
TARGET_LINK_LIBRARIES(${CLIENT_TARGET} ${TARGET_LINK_LIBS})
The CLIENT_TARGET is just a predefined target name for output.
[For windows i am using following FindAPR.cmake module (the FindAPR_windows.cmake file)](
https://svn.apache.org/repos/asf/incubator/celix/trunk/cmake/modules/FindAPR.cmake).
For linux i am using following FindAPR.cmake module (the FindAPR_unix.cmake file).
It searches for apr-1-config and executes the shell script.
In linux my APR_LIBRARIES variable looks like this:
-L/usr/lib;-lapr-1
Windows is directly using the library with its path:
{path_to_lib}/libapr-1.lib
CMake does not announce any errors for linking, as mentioned above Visual Studio does give me the LNK2019 errors when calling for any apr function.
Maybe someone does have a hint for this problem?

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