Sometimes it's important to have code work in multiple releases of MATLAB, while still taking advantage of new features when they exist. In recent articles, I've talked about the MException class and using try/catch. Here's another tool to add to your collection: verLessThan.
Contents
ver and version
The functions version and ver allow you to query for the MATLAB version and versions of additional products, as well as extra environmental information.
v = version
v = 7.5.0.342 (R2007b)
vmat = ver('matlab')vmat =
Name: 'MATLAB'
Version: '7.5'
Release: '(R2007b)'
Date: '02-Aug-2007'
vsim = ver('simulink')vsim =
Name: 'Simulink'
Version: '7.0'
Release: '(R2007b)'
Date: '02-Aug-2007'
There is additional information supplied when I ask for the information to be displayed instead of assigning it to a variable.
ver simulink-----------------------------------------------------------------------------
MATLAB Version 7.5.0.342 (R2007b)
MATLAB License Number: DEMO
Operating System: Microsoft Windows XP Version 5.1 (Build 2600: Service Pack 2)
Java VM Version: Java 1.6.0 with Sun Microsystems Inc.
Java HotSpot(TM) Client VM mixed mode
-----------------------------------------------------------------------------
Simulink Version 7.0 (R2007b)
Trademarks
------------------
MATLAB, Simulink, Stateflow, Handle Graphics, Real-Time Workshop, and xPC
TargetBox are registered trademarks and SimBiology, SimEvents, and
SimHydraulics are trademarks of The MathWorks, Inc. Other product or
brand names are trademarks or registered trademarks of their respective
holders.
verLessThan for MATLAB versions 6.0-7.3
varLessThan started shipping with the MATLAB R2007a release. To bridge the gap back to the year 2000 and MATLAB version 6.0, look at this solution from the tech support web site. There's a link near bottom to get access to verLessThan M-file backward compatible to MATLAB 6.
References
Here are the references to the blog articles I mentioned earlier.
Other Compatibility Tools
I know there are other compatibility tools on MATLAB Central as well, such as this one from Tim Davis.
Thoughts?
We make a concerted effort to not introduce incompatibilities without good reason. We also try to supply tools to help you manage and use the new tools alongside older ones. If you have any thoughts or suggestions on the topic of managing compatibility, please share them here.
Get
the MATLAB code
Published with MATLAB® 7.5
Hi Loren,
It should be noted that ver is not available in compiled code prior to R2007b. See tech solution:
http://www.mathworks.com/support/bugreports/details.html?rp=225580
Yes Matt, that’s true. There was a bug using ver with the MATLAB Compiler and it has been fixed.
–Loren
It would be very helpful if there were a MATLAB_VERSION #define’d for use in a C/C++ mexFunction. For example:
#if MATLAB_VERSION >= 7.3
#define Int mxSignedIndex
#else
#define Int int
#endif
…
Int *p = mxGetJc ( … ) ;
The new mx data type for an integer can’t be used in mexFunctions that attempt to port to older versions of MATLAB. Thus, I just use “long” and skip the use of mxSignedIndex that appeared in MATLAB 7.4 (or was it 7.3…? whichever …).
The lack of a MATLAB_VERSION makes porting a mexFunction for different versions of MATLAB (both 32-bit and 64-bit) very very tricky, particularly ones that deal with sparse matrices since the mexFunction needs to know how the integers are stored inside the sparse matrix (32 or 64 bits).
Those who write M-files don’t have to worry about this, but mexFunction authors do.
In addition, the #define for MATLAB_VERSION should be ported back to older MATLAB versions, say in a #include “mex_version.h” file that could be back-ported. This mex_version.h file would figure out the MATLAB version number using details of the kind of #define’s inside the mex.h file, such as:
#ifndef MATLAB_VERION
#ifdef mxSignedInt
MATLAB_version 7.3 (or whatever) to 7.5; use other
aspects of mex.h to figure out which one.
#else
this is MATLAB 7.2 or earlier, etc.
#endif
#else
this must be MATLAB 7.6 (or whatever) that has MATLAB_VERSION defined already
#endif
I’d write such a mex_version.h myself, but it would require some pretty deep analysis of the mex.h file and all the files it includes, to figure out what the best #if tests are. It would be best be done by someone at The MathWorks.