Add documentation on how to solve "Invalid MEX-file error" when using…

… MATLAB (#1464)

* Add FAQ entry on Invalid MEX-file error

* Add links to FAQs in MATLAB-related documentation

README.md

@@ -296,6 +296,32 @@ The `robotology-superbuild` is based on [YCM](https://github.com/robotology/ycm)
   International Journal of Semantic Computing (IJSC), Vol. 13, No. 02, 2019
 
 
+### How do I solve the "Invalid MEX-file <...>" error message on Linux when using MATLAB or Simulink libraries?
+
+If you are on Linux and you encounter errors similar to:
+~~~
+Invalid MEX-file '/home/username/Software/robotology-superbuild/build/install/mex/WBToolbox.mexa64':
+ /home/username/Software/matlab/bin/glnxa64/../../sys/os/glnxa64/libstdc++.so.6:
+version `GLIBCXX_3.4.21' not found (required by /home/username/Software/robotology-superbuild/build/install/mex/WBToolbox.mexa64)
+~~~
+when running MATLAB or Simulink libraries installed by the robotology-superbuild, to solve the problem it should be sufficient to run:
+~~~
+sudo apt install matlab-support
+~~~
+and specify your MATLAB installation directory and when there is the question "Rename MATLAB's GCC libraries?" answer "Yes".
+
+If there are no configuration question when you run , probably that means that the package is already installed. In that case, you can just reconfigure it with the command:
+~~~
+sudo dpkg-reconfigure matlab-support
+~~~
+and again, specify your MATLAB installation directory and when there is the question "Rename MATLAB's GCC libraries?" answer "Yes".
+
+If the problem persists even after following this steps, please [open a new issue in the robotology-superbuild issue tracker](https://github.com/robotology/robotology-superbuild/issues/new).
+
+
+
+
+
 Mantainers
 ==========
 

doc/cmake-options.md

@@ -306,6 +306,7 @@ For more info on configuring MATLAB software with the robotology-superbuild, ple
 ### Check the installation
 To verify that the compilation of `ROBOTOLOGY_USES_MATLAB` option was successful, try to run a script that uses
 the Matlab bindings of `yarp` and see if it executes without any error, for example:
+
 ~~~matlab
 yarpVec = yarp.Vector();
 yarpVec.resize(3);
@@ -314,6 +315,8 @@ yarpVec.toMatlab()
 ~~~~
 This scripts should print a `1 2 3` vector, but only if the `yarp` bindings are working correctly.
 
+If executing this script you obtain a "Invalid MEX-file ..." error, please check how to solve this problem in [the related FAQ question in robotology-superbuild's README](../README.md#how-do-i-solve-the-invalid-mex-file--error-message-on-linux-when-using-matlab-or-simulink-libraries).
+
 
 ## Octave
 
@@ -334,7 +337,8 @@ yarpVec.resize(3);
 yarpVec.fromMatlab([1;2;3]);
 yarpVec.toMatlab()
 ~~~~
-This scripts should print a `1 2 3` vector, but only if the `yarp` bindings are working correctly.
+This scripts should print a `1 2 3` vector, but only if the `yarp` bindings are working correctly. 
+
 
 
 ## Python

doc/matlab-one-line-install.md

@@ -20,6 +20,7 @@ vec.fromMatlab([1,2,3])
 vec.toString();
 ~~~
 
+If executing this script you obtain a "Invalid MEX-file ..." error, please check how to solve this problem in [the related FAQ question in robotology-superbuild's README](../README.md#how-do-i-solve-the-invalid-mex-file--error-message-on-linux-when-using-matlab-or-simulink-libraries).
 
 
 ### Installation on MATLAB Online