{"id":288,"date":"2023-02-23T19:34:11","date_gmt":"2023-02-23T19:34:11","guid":{"rendered":"https:\/\/jtstreib.com\/main\/?page_id=288"},"modified":"2023-02-24T00:59:13","modified_gmt":"2023-02-24T00:59:13","slug":"section-12-4","status":"publish","type":"page","link":"https:\/\/jtstreib.com\/main\/index.php\/section-12-4\/","title":{"rendered":"Section 12.4"},"content":{"rendered":"\n
\/\/ Guide to Java, Second Edition
\/\/ Copyright 2023, by J.T. Streib and T. Soma<\/pre>\n\n\n\n
public class InnerProductParallel {
   public static void main(String[] args) {
      int numThreads, vecSize;
      int innerProduct;
      innerProduct = 0;
      numThreads = Integer.parseInt(args[0]);
      vecSize = Integer.parseInt(args[1]);
      int[] a, b;
      a = new int[vecSize];
      b = new int[vecSize];
      getVec(a);
      getVec(b); 

      \/\/ parallel section
      \/\/#omp parallel num_threads(numThreads) 
             shared(numThreads, innerProduct, vecSize, a, b)
      {
         int myPart, myID, myFirstPos, myLastPos;
         int myInnerProduct;
         myInnerProduct = 0;
         myPart = vecSize \/ numThreads;
         myID = Pyjama.omp_get_thread_num();
         myFirstPos = myPart * myID;
         if(myID == numThreads-1)
            myLastPos = vecSize;
         else
            myLastPos = myFirstPos + myPart;

         \/\/ multiplication and addition 
         for(int i=myFirstPos; i<myLastPos; i++)
            myInnerProduct = myInnerProduct + (a[i] * b[i]);

         \/\/ critical section: update innerProduct
         \/\/#omp critical 
         {
            innerProduct += myInnerProduct; 
         } \/\/ end of critical section
      } \/\/ end of parallel section

      \/\/ print the contents of vectors if the size is small
      if(vecSize <= 10) {
         System.out.print(\"a = [\");
         for(int i=0; i<vecSize; i++) 
            System.out.print(a[i] + \" \");
         System.out.println(\"]\");
         System.out.print(\"b = [\");
         for(int i=0; i<vecSize; i++) 
            System.out.print(b[i] + \" \");
         System.out.println(\"]\");
      }
      System.out.println(\"Inner Product is \" + innerProduct);
   }

   public static void getVec(int[] array) {
      for(int i=0; i<array.length; i++)
         array[i] = (int)(Math.floor(Math.random() * 1000));
   }
}<\/pre>\n","protected":false},"excerpt":{"rendered":"
\/\/ Guide to Java, Second Edition\/\/ Copyright 2023, by J.T. Streib and T. Soma public class InnerProductParallel { public static void main(String[] args) { int numThreads, vecSize; int innerProduct; innerProduct = 0; numThreads = Integer.parseInt(args[0]); vecSize = Integer.parseInt(args[1]); int[] a, b; a = new int[vecSize]; b = new int[vecSize]; getVec(a); getVec(b); \/\/ parallel section \/\/#omp… Continue reading Section 12.4<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/pages\/288"}],"collection":[{"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/comments?post=288"}],"version-history":[{"count":6,"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/pages\/288\/revisions"}],"predecessor-version":[{"id":316,"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/pages\/288\/revisions\/316"}],"wp:attachment":[{"href":"https:\/\/jtstreib.com\/main\/index.php\/wp-json\/wp\/v2\/media?parent=288"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}