OpenACC-course/lab1/C/task4/task4.c

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#include <math.h>
#include <string.h>
#include "timer.h"
#define NN 1024
#define NM 1024
float A[NN][NM];
float Anew[NN][NM];
int main(int argc, char** argv)
{
const int n = NN;
const int m = NM;
const int iter_max = 1000;
const double tol = 1.0e-6;
double error = 1.0;
memset(A, 0, n * m * sizeof(float));
memset(Anew, 0, n * m * sizeof(float));
for (int j = 0; j < n; j++)
{
A[j][0] = 1.0;
Anew[j][0] = 1.0;
}
printf("Jacobi relaxation Calculation: %d x %d mesh\n", n, m);
StartTimer();
int iter = 0;
#pragma acc data copy(A), create(Anew)
while ( error > tol && iter < iter_max )
{
error = 0.0;
#pragma omp parallel for shared(m, n, Anew, A)
#pragma acc kernels
for( int j = 1; j < n-1; j++)
{
for( int i = 1; i < m-1; i++ )
{
Anew[j][i] = 0.25 * ( A[j][i+1] + A[j][i-1]
+ A[j-1][i] + A[j+1][i]);
error = fmax( error, fabs(Anew[j][i] - A[j][i]));
}
}
#pragma omp parallel for shared(m, n, Anew, A)
#pragma acc kernels
for( int j = 1; j < n-1; j++)
{
for( int i = 1; i < m-1; i++ )
{
A[j][i] = Anew[j][i];
}
}
if(iter % 100 == 0) printf("%5d, %0.6f\n", iter, error);
iter++;
}
double runtime = GetTimer();
printf(" total: %f s\n", runtime / 1000);
return 0;
}