Quantum maps with python - Installation problems and notes

Below the following topics will be addressed:

Errors when running pert_cat.py et.al (see Quantum maps)
Installation notes

In case of errors

First check if python is installed at all by typing at the shell prompt
```
   python
```
If not, you have to install python and Numeric yourself, see below.
If this is successful try to import Numeric in Python
```
   import Numeric
```
If this fails you have to install Numeric yourself, see below.
If this is also okay try to import the LinearAlgebra module
```
   import LinearAlgebra
```
If this fails one has to check the installation of Numeric ... (i.e., this can be a more difficult problem with many different reasons ...)

Installation notes

The following are brief installation notes under UNIX (using bash syntax). Usually things like this get out-dated quickly, so in case of problems (or newer versions ;-) consult the documentation of the corresponding programs.

Installation of Python

Step 1: get Python-2.2.tgz (or more recent) from the Python Homepage
Step 2: install via

    # We use ${HOME}/PYTHON as homedirectory for Python
    export PHOME=${HOME}/PYTHON
    mkdir ${PHOME}
    export PATH=${PHOME}/bin:${PATH}
    tar xzf Python-2.2.tgz
    cd Python-2.2
    ./configure --prefix=${PHOME}
    make 
    make install
    # the following is optional
    make test

Note that this will take some time to build. After the installation you should add ${PHOME}/bin to your path,

    export PATH=${PHOME}/bin:${PATH}

so that python can be found. Addtional remarks:

if you have gnu readline use it
also if you have Tcl/Tk, enable this as well in setup.py

Installation of Numeric

Step 1: get Numeric-21.0.tar.gz (or more recent) from the Numeric Homepage
(under Latest File Releases select the download under numpy)
Step 2: install via

    # If you haven't done this yet, also first execute
    export PHOME=${HOME}/PYTHON
    mkdir ${PHOME}

    # and then
    tar xzf Numeric-21.0.tar.gz
    cd Numeric-21.0 
    python setup.py install --prefix=${PHOME}

Note that this will take some time to build. (afterwards don't forget to set PYTHONPATH if necessary, see below)

Installation of IPython

For interactive work I highly recommend IPython.
Step 1: get the most recent IPython
Step 2: For example for IPython-0.2.9.tar.gz install via

    tar xzf IPython-0.2.9.tar.gz
    cd IPython-0.2.9
    python setup.py install --prefix=${PHOME}

Now you just type ipython instead of python to enjoy all the benefits of IPython.

Installation when Python is already installed

In some cases python will already be installed on your machine. To install Numeric locally under your account follow the above. To be able to import it you have to tell python where to find it,

    export PYTHONPATH=${PHOME}/lib/python2.2/site-packages/Numeric:  \
                      ${PHOME}/lib/python2.2/site-packages/

For IPython you should add ${PHOME}/bin to your path,

    export PATH=${PHOME}/bin:${PATH}

so that ipython can be found.