MATLAB 6.0 Release Notes (MATLAB Release Notes)

MATLAB Release Notes

External Interfaces/API Issues

Recompile Fortran MEX-Files

Due to changes in the MATLAB/Fortran interface, Fortran MEX-files that were built with versions of MATLAB prior to Release 12 (MATLAB 6.0) will not work unless they are rebuilt with MATLAB 6.0.

MEX File Compatibility

The Release 12 MATLAB Application Program Interface (API) has several compatibility issues relating to existing MEX-files:

C MEX-files built under MATLAB 4.x may work with MATLAB 6.0, but are no longer supported. You should rebuild these files using MATLAB 6.0.
You will need to rebuild all MATLAB 5.x C MEX-files on the IBM_RS in MATLAB 6.0 in order to run those MEX-files in MATLAB 6.0.
MATLAB 6.0 C and Fortran MEX-files will not run on previous versions of MATLAB.

Preference File Location for mex and mbuild

On Windows platforms, the mex and mbuild commands now look for their preferences file in

C:\Winnt\profiles\<user>\application data\mathworks\matlab\R12

as opposed to the location used by previous versions.

C:\Winnt\profiles\<user>\application data\mathworks\matlab

On UNIX platforms, the mex and mbuild commands now look for their preferences file in

```
/home/<user>/.matlab/R12
```

Therefore, to restore functionality to mex and mbuild, you will need to either

Run mex -setup and/or mbuild -setup (easy way), or
Manually move your options files from the directory used for preferences in previous releases to the directory now used.

Linux MEX-files

For Release 12, you must rebuild Release 11 MEX-files on Linux.

Due to compatibility issues between versions of the GNU standard C libraries, for Linux the file extension for MEX-files is now .mexglx. The file extension for Release 11 was .mexlx. This change in file extensions means that the Release 11 MEX-files for Linux will be ignored by Release 12, unless you rebuild the Release 11 MEX-files in Release 12.

SGI MEX-files

You will need to rebuild all MATLAB 5.x C MEX-files on the SGI in MATLAB 6.0 in order to run those MEX-files in MATLAB 6.0. There is no longer a difference between SGI and SGI64 MEX-files; they are all built as n32.

Unsupported Compilers

MATLAB no longer supports the following compilers:

Digital Visual Fortran version 6.0
Microsoft Visual C/C++ version 4.2

In addition, The MathWorks will drop support for following compilers in a future version of MATLAB. The MathWorks no longer tests with these compilers:

Watcom C/C++ version 11
Watcom C/C++ version 10.6

Using the move Command for ActiveX Controls

In previous versions of MATLAB, the move command returned its first two output variables in reversed order. In the following command,

```
pos = move(h);
```

the returned value pos, was [y x xsize ysize] where it should have been
[x y xsize ysize].

This has been corrected in MATLAB 6.0. If you have changed your code to accommodate the reversed order in earlier versions of MATLAB, you should correct the order of these variables for MATLAB 6.0.

Return Values for Methods Invoked on ActiveX Objects

In previous releases of MATLAB, invoking a method on an ActiveX object always returned a value of type double. Given the example,

h = actxcontrol('MWSAMP.MwsampCtrl.1');
val = invoke(h, 'GetI4');

instead of returning an int32 value in val, MATLAB converted the type of the object obtained from COM to a double.

MATLAB 6.0 returns the same type of object that was passed to it from COM during method invocation. For example, in R12, val will be an int32 value instead of a double.

This was done to be consistent with the method signature for a given method. The method signatures for all methods of an interface can be obtained using invoke on the handle to an ActiveX object. For example,

```
invoke(h)
```

will list all methods and their signatures for the mwsamp control.

If you prefer the former behavior, where MATLAB converts the return value to double, you will need to explicitly call double on the method parameter you wish to convert. For example,

```
val = double(invoke(h,'GetI4'));
```

yields the old behavior.

mex Function Now Returns Accurate Error Status

The mex syntax

```
mex myprog.c
```

now throws an error when it encounters an error condition.

The mex syntax

```
stat = mex('myprog.c')
```

now returns a nonzero value to stat when it encounters an error condition.

In the past, on Microsoft Windows platforms, mex always either successfully exited or returned zero (indicating success), regardless of whether an error had actually occurred.

To ensure code from before Release 12 works properly in Release 12, either use try/catch logic to deal with error conditions, or use a form of mex that returns an error status instead of throwing an error. Specifically

try
  mex something.c
catch
  disp(`something failed');
end

status = mex(`something.c');
if status ~= 0
  disp(`something failed');
end

Using engEvalString with GUI-Intensive Applications

If you have graphical user interface (GUI) intensive applications that execute a lot of callbacks through the MATLAB engine, you should force these callbacks to be evaluated in the context of the base workspace. Use evalin to specify that the base workspace is to be used in evaluating the callback expression, as follows.

engEvalString(ep, "evalin('base', expression)")

Specifying the base workspace in this manner ensures that MATLAB will process the callback correctly and return results for that call.

This does not apply to computational applications that do not execute callbacks.

Starting MATLAB in gdb on GLINUX

If you debug MATLAB using gdb on a GLINUX system, your session will stop execution whenever it creates a new thread. You can avoid these interruptions by telling the system not to stop on SIGCONT events. You can then proceed to debug your MATLAB code using nodesktop mode. You will still be notified whenever a new thread is created, but your session will continue to run without interruption.

Use the following statement in gdb to turn off triggering on SIGCONT events.

```
handle SIGCONT nostop
```

You can choose to debug in gdb without specifying SIGCONT nostop, but you will have to type continue at each interruption to proceed with your session. The following is a sample debug session in which SIGCONT nostop is specified.

% matlab -Dgdb

(gdb) handle SIGCONT nostop
Signal Stop Print Pass to program Description 
SIGCONT No   Yes   Yes             Continued

(gdb) run -nodesktop
[New Thread 4219]
Program received signal SIGCONT, Continued. 
[New Thread 4220]
Program received signal SIGCONT, Continued.

MEX-File Extension Changes

The MEX-file extensions have changed for the Linux, SGI, and HP700 platforms for MATLAB 6.0.

Platform
Pre-6.0 Extension
Extension for MATLAB 6.0

Linux
.mexlx
.mexglx

SGI
.mexsg
.mexsg (no change)

SGI64
.mexsg64
.mexsg

HPUX 11.x
.mexhp7
.mexhpux

HPUX 10.20
.mexhp7
.mexhp7 (no change)

Platform	Pre-6.0 Extension	Extension for MATLAB 6.0
Linux	`.mexlx`	`.mexglx`
SGI	`.mexsg`	`.mexsg` (no change)
SGI64	`.mexsg64`	`.mexsg`
HPUX 11.x	`.mexhp7`	`.mexhpux`
HPUX 10.20	`.mexhp7`	`.mexhp7` (no change)

Obsolete C Language MEX Functions

The following API function is obsolete and should not be used in MATLAB programs. This function may not be available in a future version of MATLAB.

```
mexAddFlops
```

Programming and Data Types Issues Creating Graphical User Interfaces - Upgrade Issues