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--- magistraleinformaticanetworking:spm:exercise1617spm [12/10/2016 alle 13:48 (9 anni fa)] – creata Marco Danelutto
+++ magistraleinformaticanetworking:spm:exercise1617spm [12/10/2016 alle 15:36 (9 anni fa)] (versione attuale) – [Hints] Marco Danelutto
@@ Linea 7: / Linea 7: @@
 Check the correctness of the result against result computed sequentially.
 Plot scalability curve for the program.
+==== Hints ====
+  * use <code>int atoi(char *)</code> to convert the command line arguments to integers
+<code>
+  int main(int argc, char * argv[]) {
+    int n = atoi(argv[1]);
+    int m = atoi(argv[2]);
+    ...
+  }
+</code>
+  * use the <code>std::chrono</code> library to get time before and after the parallel computation and to compute the elapsed time:
+<code>
+  std::chrono::time_point<std::chrono::system_clock> start, end;
+  start = std::chrono::system_clock::now();
+  ...
+  end = std::chrono::system_clock::now();
+  std::chrono::duration<double> elapsed_seconds = end-start;
+</code>
+  * use plain <code>rand</code> to generate random numbers in the two matrixes:
+<code>
+  srand(123);
+  for(....) {
+      ... = ((float) (rand() % MAX)) / ((float) RAND_MAX);
+</code>
+====== Average neighbours =====
+Write a program that generates an N by N matrix A and then executed a number Niter of iterations where at each iteration A[i][j] is substituted by the average of A[i][j] and the four neighbours (north, south, east and west). At the borders, the missing elements in the neighbourhood have to be assumed to be 0. All the new A[i][j] values must be computed summing up values **at the current iteration** for the neighbours.
+Computation of the single iteration should be parallelized using threads.