finished #1 and #2

git-svn-id: svn://anubis/gvsu@188 45c1a28c-8058-47b2-ae61-ca45b979098e

cs677/hw7/hw.tex

@@ -21,12 +21,37 @@
 \noindent
 \begin{enumerate}
 \item[1.]{
-    in progress
+    Break the ``parallel region'' into a function accepting a \texttt{void *}
+    parameter.
+    Before the ``parallel region'' create a \texttt{for} loop which loops
+    \textit{n} times (where \textit{n} is the number of threads),
+    invoking \texttt{pthread\_create()} once for each thread.
+    Any variables local to the function containing the ``parallel region''
+    that the ``parallel region'' function needs access to
+    would have to be stored as pointers in a structure whose address was
+    passed as an argument to the thread function.
+    Then, the thread would run the code in the ``parallel region''.
+    After the region, a \texttt{for} loop would exist to loop over all
+    the threads created in the first loop and execute \texttt{pthread\_join()}
+    for each one.
 }
 
 \vskip 2em
 \item[2.]{
-    in progress
+    Each thread could store its result into an array indexed by its ID.
+    Then, when computation is complete, a regular \texttt{for} loop
+    within an OpenMP parallel region could iterate
+    $\lceil \log_2 n \rceil$ times.
+    In the first iteration, threads where $ID\mod 2 = 0$ would perform
+    the reduction operation on their array value and the array value
+    at index $ID + 1$ while the rest of the threads are idle.
+    In the second iteration, threads where $ID\mod 4 = 0$ would perform
+    the reduction operation on their array value and the array value
+    at index $ID + 2$ while the rest of the threads are idle.
+    This process would repeat (doubling the mod value and offset index
+    each time) until the reduction operation has been
+    performed to produce the final result value at index 0 of the
+    array.
 }
 
 \end{enumerate}