\section{The Parser Window}\index{Parser window}\index{window, Parser}\label{parser}
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\begin{figure}[H]
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\centerline{\psfig{figure=ps/parser.ps,height=228pt}}
\caption{\label{parserwin}
The Parser window.
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\end{figure}

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\begin{description}

\item[Window title:] DsTool: Dynamical system definition
\item[Function:] The Parser window allows the user to define a dynamical system without writing C code and 
  	compiling a new model into DsTool.
\item[Description:]  The Parser window is opened by selecting the Parser option from the Models 
	menu button located in the Command window.  The user can load or save model (vector field or 
	mapping) definitions, build the current model into DsTool as the current 
        dynamical system, or generate C code which can be subsequently compiled into DsTool.
\item[Panel items:] \mbox{}
	\begin{itemize}
	\item Directory read-write text field:
		Displays the currently selected directory which DsTool will use to save to or read
		from.   The default is the current value of the UNIX 
		environmental variable \unix{DSTOOL\_DATA\_DIR}, or if that is not set, the current
		working directory.
	\item Filename read-write text field:
		Displays the currently selected filename which to write to or read from.   
		This should be a single word of no more than 30 characters.
		The default value is ``model.def''. 
	\item Model name read-write text field:
		Displays the currently selected string describing the model.   The default value
		is ``parsed\_model''.
	\item Vector Field / Mapping exclusive selection:
		Allows the user to choose whether the dynamical system should be interpreted as a vector field
		or a mapping.  The default is to interpret it as a vector field. 
	\item Dynamical system definition text pane:\index{parsed dynamical system}
		Displays the definition for the dynamical system in simplified notation.   See section 
		\ref{def_ds_parser} for more information on how to define 
		a dynamical system in this section.  The default is to display text describing
		the Lorenz system. 
%		Lines that begin with the \# symbol are comments, and are ignored in the definition.   Specifying 
%		the definition for a vector field entails giving equations for the time derivatives 
%		of the phase space variables, specifying initial values for every appearing parameter and variable,
%		and giving ranges of values for each phase space variable and parameter.   The equations for 
%		the time derivatives of the phase space variables must be written as elementary functions 
%		of the phase space variables and the parameters, with each derivative appearing alone on the
%		left hand side of an equation.  Variables and parameters separated by a space will be 
%		interpreted as being multiplied together.   The initial values for the parameters and phase 	
%		space variables should 
%		be given in a list starting with the word ``INITIAL'', and followed in succession by the 
%		parameters and variables and their initial values.   Parameters which appear in the dynamical 
%		system definition, but which are not given initial values will have default value 1.
%		Variables which appear in the dynamical systems definition but which are not given initial
%		values will have default value 0.  
%		The ranges of the phase space variables and parameters should be given in a list starting with the word
%		``RANGE'', and followed in succession by the variables and a minimum and maximum value 
%		for that variable.   Variables and parameters which are not given ranges at this time will get the 
%		default values of minimum and maximum values of -10.0 and 10.0 respectively.  
	\item Load window button:\index{window, Files}\index{Files window}
		Opens and brings to the foreground the File window for loading the
		model file specified by the Filename text field, 
		in the directory specified by the Directory text field.
	\item Save window button:
		Opens and brings to the foreground the File window for saving the model definition
 		given in the dynamical system definition text.  The model definition will be saved
		to the directory specified by the Directory text field under the filename specified by the 
		Filename text field.   
	\item Write C code command-window button:\index{C code, automatically generated}
		Parses the textual information in the dynamical system definition text pane and generates 
		C code, then opens and brings to the foreground the C Code 
		window\index{C Code window}\index{window, C Code}.
	\item Build model command button:
		Incorporates the model defined in the dynamical system definition text pane 
		into DsTool as the current model.  If the model definition is inadequate, an error message is printed.
	\item Clear command button:		
		Clears the dynamical system definition text pane.   
	\item Dismiss command button:
		Closes the Parser window. 
%  The information in the Parser window will revert back to the 
%		default when the window is closed.
        \end{itemize}
\end{description}
