156 
For more details we refer the reader to the literature, for instance \Ref{Zienc,NumHand}. 
For more details we refer the reader to the literature, for instance \Ref{Zienc,NumHand}. 
157 


158 
The \escript solver we want to use to solve this problem is embedded into the python interpreter language. So you can solve the problem interactively but you will learn quickly 
The \escript solver we want to use to solve this problem is embedded into the python interpreter language. So you can solve the problem interactively but you will learn quickly 
159 
that is more efficient to use scripts which you can edit with your favourite editor. 
that is more efficient to use scripts which you can edit with your favorite editor. 
160 
To enter the escript environment you use \program{escript} command\footnote{\program{escript} is not available under Windows yet. If you run under windows you can just use the 
To enter the escript environment you use \program{escript} command\footnote{\program{escript} is not available under Windows yet. If you run under windows you can just use the 
161 
\program{python} command and the \env{OMP_NUM_THREADS} environment variable to control the number 
\program{python} command and the \env{OMP_NUM_THREADS} environment variable to control the number 
162 
of threads.}: 
of threads.}: 
176 
>>> print "2+3=",x 
>>> print "2+3=",x 
177 
2+3= 5 
2+3= 5 
178 
\end{python} 
\end{python} 
179 
We refer to the python users guide if you not familar with python. 
We refer to the python users guide if you not familiar with python. 
180 


181 
\escript provides the class \Poisson to define a Poisson equation \index{Poisson equation}. 
\escript provides the class \Poisson to define a Poisson equation \index{Poisson equation}. 
182 
(We will discuss a more general form of a PDE \index{partial differential equation!PDE} 
(We will discuss a more general form of a PDE \index{partial differential equation!PDE} 