Matlab setup

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Preparing Matlab to use psychWithJava

This section explains how to prepare Matlab for development with psychWithJava package. Setup involves two steps: Setting the JVM version and setting the javaclasspath variable. OS specific instructions are given in alphabetical order.

Step 1: Set the JVM version

Launch Matlab on your system and check the Java version. Type

version -java

and press enter. If the reported Java version is not 5.0 (or 1.5) then you will have to configure your system to make Matlab use version 5.0. This is explained here or here. I give the current instructions below, but for most recent instructions you should follow the above links.

Linux:

First find out where your JVM is installed. This is where the run time environment is located. If you followed the instructions in the The Guide to Psychophysics Programming with Java, Chapter 1: Introduction, then the path should be
```
/opt/jdk1.5/jre
```
(note to Linux users: even though I recommended using version 6.0 (or 1.6) in Chapter 1: Introduction of the Guide, with Matlab you should use jdk1.5 for now, because the beta version 1.6 doesn't properly work with Matlab.)

Next set the MATLAB_JAVA variable. Open a terminal and type
```
echo $SHELL
```
and press enter. If the response indicates that you are using bash, type
```
export MATLAB_JAVA=<path to JVM>
```
and press enter. If your shell is tcsh, type
```
setenv MATLAB_JAVA <path to JVM>
```
and press enter. Then start matlab as usual and check whether Java version is now 1.5. You may need to start Matlab from the same terminal as you set the MATLAB_JAVA environment variable. If you want to add the setting to your start up script so that you don't have to manually set it everytime you use Matlab, you can put the above commands in your .bash_profile or .tcshrc file. More on start-up scripts.
Next: Step 2: Set the javaclasspath

Mac OS X:

MATLAB always uses the default version of the JVM installed on the computer. By default Mac OS X uses the older 1.4 version. But if you followed the instructions for Mac OS X users on Installation section and installed the most recent Revision of Java, your preferred version should be version 5.0.
However if you don't want to install the most recent revision and/or change the system wide default version from 1.4 to 5.0, you must specify the JAVA_JVM_VERSION environment variable. Open a terminal and find out your SHELL. More on finding out what your shell is here. If your shell is bash, type
```
export JAVA_JVM_VERSION=1.5
```
and press enter. If your shell is tcsh type
```
setenv JAVA_JVM_VERSION 1.5
```
and press enter. Start Matlab and check that Java version is now 1.5. If you want to add the setting to your start up script so that you don't have to manually set it everytime you use Matlab you can put the above commands in your .bash_profile or .tcshrc file. More on start-up scripts.
Next: Step 2: Set the javaclasspath

MS Windows 2000/XP:

Open Control Panel

Click System

Choose the Advanced tab and then click the Environment Variables button.
You now can set (or add) the MATLAB_JAVA system environment variable to the path of your JVM. Note that JVM resides in a directory named jre. It can be under the main java directory or it can be seperate.

Step 2: Set the javaclasspath

You can use the classes of psychWithJava from any directory on your system. However, to do so you have to include the path to your java packages in the javaclasspath variable. In order to find class definitions, Matlab searches directories and files that are set in the javaclasspath variable. There are two ways of setting the javaclasspath in Matlab. One is static, other is dynamic. Static one sets the path permenantly until you change the settings. That is, you don't need to set the path every time you launch Matlab. Dynamic path is temparory and lives only during the session in which you set it.

Setting a dynamic path.

here

Launch Matlab. Add the psychWithJava package into the javaclasspath. Type
```
javaaddpath <full_path_to_psychWithJava> 
```
and press enter. <full_path_to_psychWithJava> is the full path to the psychWithJava.jar file. For example /home/yourname/javaClasses/psychWithJava.jar on Linux, or /Users/yourname/javaClasses/psychWithJava.jar on Mac OS X, or C:\yourfolder\javaClasses\psychWithJava.jar on MS Windows.

Make sure that the path is added to the classpath. To check the java classpath (in Matlab command window), type
```
javaclasspath
```
and press enter. Names of all packages in the current java class path should be listed including psychWithJava package.

Setting the static path

here

To make changes in the static path you have to edit the classpath.txt file. There may be two versions of that file: local and shared. If you edit the shared one that will affect all users who share the same MATLAB root directory. Local file can be found/created in your own startup directory. When MATLAB starts up, it looks for classpath.txt first in your startup directory, and then in the default location. It uses the file it finds first. To see which classpath.txt file is currently being used by your MATLAB environment, launch Matlab and type
```
which classpath.txt
```
press enter.

Edit the classpath.txt file either with Matlab editor or with another editor of your choice on your system. (On Linux or Mac OS X you may have to have administrative previliges to edit the shared classpath.txt file.) Add the full path to the psychWithJava.jar file. For example /home/yourname/javaClasses/psychWithJava.jar on Linux, or /Users/yourname/javaClasses/psychWithJava.jar on Mac OS X, or C:\yourfolder\javaClasses\psychWithJava.jar on MS Windows.

Exit from Matlab and re-launch it. Make sure that the <path_to_your_java_packages> is added in the javaclasspath. To check the java classpath type (in Matlab command window)
```
javaclasspath
```
and press enter. Names of all packages in the current java class path should be listed including psychWithJava package.

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