added fano factor exercise

pointprocesses/exercises/pointprocesses01.tex

@@ -173,7 +173,8 @@ jan.benda@uni-tuebingen.de}
       \colorbox{white}{\includegraphics[width=1\textwidth]{isihist}}
     \end{solution}
   
-    \part XXX Add return map!!! XXX Write a function that computes and plots the serial
+    % XXX Add return map!!! XXX
+    \part Write a function that computes and plots the serial
     correlations of interspike intervals for lags upto
     \code{maxlag}. The serial correlations $\rho_k$ for lag $k$ of the
     interspike intervals $T_i$ are the correlation coefficients
@@ -192,6 +193,28 @@ jan.benda@uni-tuebingen.de}
       \colorbox{white}{\includegraphics[width=1\textwidth]{serialcorr}}
     \end{solution}
 
+    \part Write a function that counts and returns the number of
+    spikes in windows of a given width $W$.
+
+    Use this function to generate a histogram of spike counts for the
+    data of the three types of neurons. Use 100\,ms for the window
+    width.
+    \begin{solution}
+      \lstinputlisting{../code/spikecounts.m}
+      % XXX
+    \end{solution}
+
+    \part Write a function that computes for a range from window
+    widths the mean, the variance and the Fano factor of the
+    corresponding spike counts.  The function should the generate two
+    plots. One showing the spike count variance in dependence on the
+    mean spike count. The other plot showing the Fano factor as a
+    function of window width.
+    \begin{solution}
+      \lstinputlisting{../code/fanoplot.m}
+      % XXX
+    \end{solution}
+
   \end{parts}
   
 \end{questions}