Ατζέντα εργαστηρίου Παράλληλου Προγραμματισμού 14/5/2021

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Ατζέντα εργαστηρίου Παράλληλου Προγραμματισμού 14/5/2021

Στο gist αυτό θα αναρτηθούν λύσεις και υποδείξεις κατά τη διεξαγωγή του εργαστηρίου.

S10.c

#include <stdio.h>
#include <stdlib.h>

// compile with: gcc -O2 -Wall pi-integral.c -o pi-integral


#define N 1000000	// integration steps

int main() {
double pi,w,sum,x;

  w = 1.0/N;	// integration step
  
  sum = 0.0;
  for (int i=1;i<=N;i++) {
    x = w*(i-0.5);	// midpoint
    sum += 4.0/(1.0+x*x); // NOTE: without mult by step (w), done later
  }
 
  pi = w*sum;
  
  printf("Computed pi=%.10f\n",pi);
  return 0;
}

S20.c

#include <stdio.h>
#include <stdlib.h>

#include <omp.h>

// compile with: gcc -fopenmp -O2 -Wall pi-integral-omp3.c -o pi-integral-omp3


#define N 1000000	// integration steps

int main() {
double pi,w,sum,x;

  w = 1.0/N;	// integration step
  sum = 0.0;
  
  #pragma omp parallel for shared(w) reduction(+:sum) private(x)
  for (int i=1;i<=N;i++) {
    x = w*(i-0.5);	// midpoint
    sum += 4.0/(1.0+x*x); // NOTE: without mult by step (w), done later
  }

  pi = w*sum;
  
  printf("Computed pi=%.10f\n",pi);
  return 0;
}

S30.c

#include <stdio.h>
#include <stdlib.h>

#include <omp.h>

// compile with: gcc -fopenmp -O2 -Wall pi-integral-omp.c -o pi-integral-omp


#define N 1000000	// integration steps

int main() {
double pi,w,sum,x;

  w = 1.0/N;	// integration step
  pi = 0.0;
  sum = 0.0;
  
  #pragma omp parallel shared(w,pi) firstprivate(sum)
  {
  
    #pragma omp for private(x) 
    for (int i=1;i<=N;i++) {
      x = w*(i-0.5);	// midpoint
      sum += 4.0/(1.0+x*x); // NOTE: without mult by step (w), done later
    }
 
    #pragma omp critical
    {
      pi += w*sum;
    }
    
  }
  
  printf("Computed pi=%.10f\n",pi);
  return 0;
}

S40.c

// compile with: gcc -fopenmp -O2 -Wall tasks-omp.c -o tasks-omp

#include <stdio.h>
#include <stdlib.h>

#include <omp.h>


int main() {

  #pragma omp parallel
  {
  
    #pragma omp single
    {
      
      #pragma omp task
      printf("A\n");

      #pragma omp task
      printf("B\n");

      printf("C\n");
      
    }
    
  }

  return 0;
}

S50.c

// compile with: gcc -fopenmp -O2 -Wall tasks-omp-wait.c -o tasks-omp-wait

#include <stdio.h>
#include <stdlib.h>

#include <omp.h>


int main() {

  #pragma omp parallel
  {
  
    #pragma omp single
    {
      
      #pragma omp task
      printf("A\n");

      #pragma omp task
      printf("B\n");

      #pragma omp taskwait
      printf("C\n");
      
    }
    
  }

  return 0;
}