These instructions explain how to compile VLFeat from sources. While this is necessary in order to develop or modify VLFeat, using the pre-compiled binaries will work in most other cases.
VLFeat is largely self-contained and hence easy to compile. While certain features such as multi-core computation and vector instruction support may require specific compilers, most compilers and environments should be capable of producing fully functional version of the library. Compiling MATLAB or Octave support requires the corresponding applications to be installed too.
Compiling for UNIX-like platforms (e.g. GNU/Linux, Mac OS X) assumes that the standard GNU toolchain is available. In particular, while compilers other than GCC can be used, the compilation scripts require GNU/make.
To compile the library, it is usually sufficient to change to
VLFeat root directory, denoted VLFEATROOT
in the
following, and type make
:
The make script attempts to automatically detect the host architecture and configure itself accordingly. If the architecture is not detected correctly, it can be specified manually. For instance
compiles for GNU/Linux 32-bit. make help
can be used
to obtain a list of other useful options. You can also use make
info
to obtain a list of the configuration parameters used by
the Makefile, which might allow you do debug any potential issue.
In order for MATLAB support to be compiled, the
MATLAB mex
script must be in the current path. If it is
not, its location must be passed to make
as
follows. First, determine MATLAB's root directory by running a MATLAB
session and issuing the matlabroot
command. Let MATLABROOT
denote the returned path
(e.g. /Applications/MATLAB_R2009b.app/
). The mex
script is usually located in MALTABROOT/bin/mex
. Then run
the compilation with the command
VLFeat must be compiled for the architecture used by MATLAB (run
MATLAB's computer
command to obtain this information). On
Mac OS X it is often necessary to turn on 64-bit support explicitly by
setting ARCH=maci64
as both the 32 and 64 bit versions
are plausible targets on 64-bit machines.
Octave support is still experimental. Similarly to MATLAB, Octave
requires compiling MEX files. This can be turned on by passing to make
the path to the mkoctfile
command:
Recent changes to Mac OS X toolkit that ships with Xcode have made compilation of VLFeat slightly more complex. Out of the box, Xcode 5.0 on Mac OS X Mavericks, for example, incorporates the clang compiler but not the GCC compiler. While VLFeat has been updated to use clang in this case, it is worth noting that this compiler does not yet support the OpenMP standard, meaning that multi-core computations would be disabled in this case.
Compiling OpenMP can be achieved by using the GCC compiler, for
example obtaining it from MacPorts. However, anything more recent that
GCC 4.2 will use the MacPorts runtime (C and C++). Since MATLAB links
to the OS X native C and C++ runtime, this breaks the compatibility of
VLFeat MEX files with MATLAB. In particular, while VLFeat does not use
C++, MEX files do as the MEX API is coded in C++ internally (in
particular MEX files are coded with the -fexception
option as MEX API calls can throw exceptions, even though they look
like regular C functions). In short, mixing C++ runtimes will cause
MATLAB MEX files to crash every time an error is generated.
The easiest solution at present is to use
the gcc-apple-4.2
from MacPorts. Unfortunately, this
version does not support AVX instructions, but supports OpenMP and
creates binaries that are MATLAB compatible.
MATLAB 2009b for Snow Leopard has added 64 bit mex support and a
corresponding extension mexmaci64
. VLFeat now supports
compiling for this platform, but the architecture must be specified
manually when compiling, either like:
or
Unfortunately, MATLAB 2009b's mex
script has a bug
that must be manually fixed in order for this procedure to work
correctly. It is recommend to make backup of the mex
script before attempting this. Th fix the bug, edit the
MATLABROOT/bin/mex
script by cutting the line:
and pasting it after the processing of options:
For Windows, the library bundles an NMake makefile
(Makefile.mak
). In order to use it, you must edit
Makefile.mak to adjust the values of a number of configuration
variables to match your setup. Once you have done that, start the
Visual Studio Command Prompt and type
For Windows platform, it is also possible to compile just the
MATLAB MEX files from within MATLAB (using the vl_compile
command). This is meant to help less experienced users that may need
to recompile the mex file due to binary incompatibilities with older
MATLAB versions.
Use nmake /f Makefile.mak
.
Without /f
, nmake will default to the wrong
makefile.
This error is usually caused by attempting to compile outside of the Visual Studio Command Prompt.