some more on the python part

programming/python_lecture_en/programming.tex

@@ -10,6 +10,26 @@ strong community support. Most packages are developed by open-source
 enthusiasts who are willing to share their code and knowledge thus,
 answers to most problems can be found with a simple internet search.
 
+\begin{important}[What is Python?]
+  It is important to understand what Python is and what it is
+  not. After installing python on a machine, one may expect to find an
+  elaborated graphical user interface or so called \enterm{Integrated
+    Development Environment, IDE} as e.g known in \matlab{}. You can
+  have it, if you want but this is not the Python core. Python is a
+  programming language, it defines the \enterm{syntax}, the grammar
+  and the keywords of the language, as well as the
+  \enterm{interpreter} that interprets your commands and executes
+  them. With the installation you get the python interpreter that,
+  called to work will open a console interface that can be used to
+  execute commands. Throughout the whole introduction we will use a
+  python console, or the command line. All examples should work with
+  the simplest python console. It is, however, nicer to use e.g. the
+  \emph{ipython} console for it offers some more convenience
+  methods. For bigger programs IDEs (e.g. spyder, pycharm, etc. ) come
+  in handy but they are building on top of Python, they are not
+  Python.
+\end{important}
+
 \section{Variables and Datatypes}
 
 Befor we can start to solve programming problems we have to know a few
@@ -20,15 +40,15 @@ basic concepts and the python syntax will be introduced.
 
 A \enterm{variable} is basically a pointer to a place in a computer's
 memory. This pointer has a human readable name, or label, and a
-\enterm{datatype} (figure \ref{variablefig}). In the memory the
+\enterm{data type} (figure \ref{variablefig}). In the memory the
 variable's content is encoded as a pattern of \enterm[bit]{bits} (a
 sequence of zeros and ones). Upon access of the variable's content the
-stored datatype is used to interpret the \enterm{bit pattern}. That is,
-the same bit pattern may be interpreted in different ways depending on
-the datatype. In the example shown in figure \ref{variablefig} the
-same bitpattern is stored but the interpretation as an 8-bit
-\enterm{integer} leads to the numeric value of 38 while an
-interpretation as a \enterm{character} lead to the ampersand symbol. 
+stored data type is used to interpret the \enterm{bit pattern}. That
+is, the same bit pattern may be interpreted in different ways
+depending on the data type. In the example shown in figure
+\ref{variablefig} the same bitpattern is stored but the interpretation
+as an 8-bit \enterm{integer} leads to the numeric value of 38 while an
+interpretation as a \enterm{character} lead to the ampersand symbol.
 
 \begin{figure}
   \centering
@@ -54,23 +74,46 @@ Variables can be created at any time at any place in a python
 program. Listing \ref{varListing1} shows different ways to do this:
 
 \begin{lstlisting}[label=varListing1, caption={Creating variables.}, language=python]
-w = 3.1415
-x = 38
-y = 'A'
-z = None
+In[0]: w = 3.1415
+In[1]: x = 38
+In[2]: y = 'A'
+In[3]: z = None
 \end{lstlisting}
 
-Line one creates 
-Die Zeile 1 kann etwa so gelesen werden:''Erzeuge eine Variable mit
-dem Namen \varcode{x} und weise ihr den Wert 38 zu''.  Das
-Gleichheitszeichen ist der sogenannte
-\codeterm{Zuweisungsoperator}. Zeile 5 definiert eine Variable \varcode{y}, der
-ein leerer Wert zugewiesen wird. Da \matlab{}, wenn nicht anders
-angegeben, immer den \codeterm{double} Datentypen benutzt, haben beide
-Variablen diesen Datentyp. In Zeile 9 wird der Variablen \varcode{z} der Buchstabe
-``A'' zugewiesen. \varcode{z} ist nicht ein Flie{\ss}kommazahl von Typ \codeterm{double},
-sondern ein \codeterm{character} (Zeichen).
+Line one creates a simple variable named 'w' that contains the value
+$3.14.15$. The command can be read as ``Create a variable named
+\varcode{w} and assign the value $3.1415$ to it.'' The equals sign in
+this context is called the \codeterm{Assignment operator} that is used
+when a value is \emph{assigned} to a variable.  The following lines
+create further variables containing differen values. Python belongs to
+the class of so called \codeterm[interpreted language]{interpreted
+  languages}, i.e. a command (like those in listing\ref{varListing1})
+is prompted, the Python \coderterm{interpreter} executes it, creates
+the variable, checks for the type of data to be stored and assigns the
+value. If we want to check for the variables that have been created or
+find out their data type we can ask for this information by the
+commands in listing \ref{varListing2}
+
+\begin{lstlisting}[label=varListing2, caption={Checking for variables and data types.}]
+In [4]: who
+w	x	y	z	
+
+In[5]: whos
+Variable   Type        Data/Info
+--------------------------------
+w          float       3.1415
+x          int         38
+y          str         A
+z          NoneType    None
+
+In[6]: type(w)
+Out[6]: float
+
+In[7]: type(x)
+Out[7]: int
+\end{lstlisting}
 
+To simply list the names of all \enterm{declared} variables, the command \code{who} can be used, in the \emph{ipython}
 Der Datentyp einer Variable kann mit \code{class()} abgefragt werden.
 Eine Liste aller definierten Variablen gibt \code{who}
 zur\"uck. Detailliertere Informationen \"uber Variablen zeigt