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varlog.w

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+\subsection{VarLog}
+This is a lillte helper class which can be used to keep  a log of a
+variable. A variables value is stored together with time information in a
+list. Various functions allow to interact with this list and retrieve the
+log. For the list the lld  package is used again. Thus the only data
+required by this module is the integer ID of the list. 
+
+The following functions are provided:
+
+@d logint @{
+/*---------------------------- birth and death ----------------------------*/  
+   typedef struct __VarLog *pVarLog;
+
+   int VarlogInit(pVarLog *self);
+   int VarlogDelete(pVarLog self);
+/*----------------------------- operation -------------------------------*/
+   int VarlogClear(pVarLog self);
+   int VarlogAdd(pVarLog self, float fVal);
+/*------------------------------ data recovery -------------------------*/
+   int VarlogLength(pVarLog self, int *iLength);
+   int VarlogGetTime(pVarLog self, time_t *tTime);
+   int VarlogGetVal(pVarLog self, float *fValues);
+   int VarlogGetMean(pVarLog self, float *fMean, float *fStdDev);
+/*------------------------------ interpreter ---------------------------*/
+   int VarlogWrapper(pVarLog self, int *iSwitch, SConnection *pCon, 
+                     char *subcommand, char *sub2,char *pVarName);
+@}
+
+All functions return 1 on success, 0 on failure if not mentioned otherwise.
+
+\begin{description}
+\item [ValogInit] creates a new varlog and prepares for data collection.
+Only parameter is a pointer to an int which will be initialised to the list
+ID to use.
+\item [VarlogDelete] deletes a varlog and frees the list. Single parameter
+is a pointer to an int holding the ID of the list to kill.
+\item [VarlogClear] clears old logged data but keeps the varlog alive for
+further data collection.
+\item [VarlogAdd] adds the float value fVal to the log denoted by iList. The
+time stamp will be generated automatically. 
+\item [VarlogLength] retrieves the length of the current log.
+\item [VarlogGetTime] retrieves the array of time stamps as provided by the
+system function time  from the log.
+\item [VarlogGetVal] retrieves the array of  values from the log.
+\item [VarlogGetMean] retrieves the mean value of the values from the log
+denoted by iList  and their standard deviation.
+\item [VarlogWrapper] is a function which may be invoked from an object 
+wrapper function in order to interpret and handle the var logs subcommands.  
+Parameters are: the varlog list, a switch variable which will be set to 1
+if logging is enabled and to 0 if not, a connection object to which data
+ will be written and finally the subcommand to evaluate.
+\end{description}
+
+@o varlog.h @{
+/*--------------------------------------------------------------------------
+                          V A R L O G
+  
+  A module which keeps  a log of a variable.
+
+  Mark Koennecke, September 1997
+
+  copyright: see implementation file
+ 
+----------------------------------------------------------------------------*/
+#ifndef SICSVARLOG
+#define SICSVARLOG
+#include <time.h>
+@<logint@>
+#endif
+@}
+
+
+
+