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4.18_omp_montecarlo.c
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4.18_omp_montecarlo.c
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/*
* Name : Tri Wanda Septian
*
* How to compile the source code (Linux)
* $gcc -fopenmp -o outfile sourcecode.c
*
* 4.18*: Repeat exercise 4.17, but instead of using a separate thread to generate random points, use OpenMP to parallelize the generation of points.
* Be careful not to place the calculation of phi in the parallel region, since you want to calculate phi only once.
*/
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <omp.h>
int i = 0; //loop counter
int count = 0; //count holds all the number of how many good coordinates
double x,y; //x,y value for thre random coordinate
double z; //used to check if x*x+y*y <=1
int totalpoints; //number if iterations per FOR LOPP
void *runner(void *param){
#pragma omp parallel private(x,y,z,i) shared(count)
//The omp parallel directive explicitly instructs the compiler to parallelize the chosen block of code.
{
srandom((unsigned int)time(NULL) ^ omp_get_thread_num());
#pragma omp for
//initialize random number of x and y
for (i=0; i< totalpoints; i++){
x = (double)rand() / RAND_MAX; //generate random x coordinate number
y = (double)rand() / RAND_MAX; //generate random y coordinate number
z = x*x+y*y;
if(z<=1){
count++;
}
}
}
}
int main(int argc, char *argv[]){
pthread_t thread;
printf("\nWelcome to Thread Process with Monte Carlo Technique and OpenMP\n");
printf("\nName : Tri Wanda Septian\n");
if(argc !=2 ){
fprintf(stderr,"\nUsage : openmp.out <integer value>\n");
return -1;
}
if (atoi(argv[1]) < 0){
fprintf(stderr,"\n%d must be >= 0\n",atoi(argv[1]));
return -1;
}
int numberIter = atoi(argv[1]); //number if iterations per FOR LOPP
totalpoints = numberIter;
pthread_create(&thread,NULL,&runner, NULL); //create the thread
pthread_join(thread,NULL);//wait forthre thread to exit
double phi = 4*((double)count/(double)totalpoints); //phi calculation formula
printf("\nNumber of trials: %d, estimate of phi is %g \n",totalpoints,phi);
}