integral2_openmp.c 3.27 KB
 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 ``````// calculate integral using client-server model // compile: gcc -fopenmp integral2_openmp.c -lm // usage: ./a.out trial# thread# // note: trial# must be multiple of CHUNK_SIZE #include #include #include #include #include #define CHUNK_SIZE 1000 // w is weight function double w(double x, double y) { return exp( - ( x*x + y*y ) ); } void generator(double * x, double * y) { double xt, yt, ratio, tmp ; double delta = 0.5 ; tmp = (double)rand() / (double)RAND_MAX ; // update x by adding a multiples of delta , (2 * tmp - 1) creates a number between -1.0 and 1.0 xt = (*x) + delta * (2 * tmp - 1) ; tmp = (double)rand() / (double)RAND_MAX ; // update y by adding a multiples of delta , (2 * tmp - 1) creates a number between -1.0 and 1.0 yt = (*y) + delta * (2 * tmp - 1) ; // compare updated x,y values with old x,y values, accept or reject updated values as new values according to weight function ratio = w(xt, yt ) / w(*x, *y) ; tmp = (double)rand() / (double)RAND_MAX ; if(ratio > tmp ) { *x = xt ; *y = yt ; } } //f is the function to be integrated double f(double x, double y) { return M_PI * ( x*x + y*y ) ; } int main(int argc, char* argv[]) { double x, y ; double * x_array ; double * y_array ; double sum = 0.0 ; int count = atoi(argv[1]); // how many random number will generated int tnumber = atoi(argv[2]); // tnumber is total thread number, myrank is rank of each thread x_array = malloc(sizeof(double) * count); y_array = malloc(sizeof(double) * count); int generated = 0 ; int consumed = 0 ; #pragma omp parallel num_threads(tnumber) { int myrank = omp_get_thread_num(); int i, j ; int start_index; double local_sum = 0 ; if(myrank == 0 ) //if master thread then generate random numbers, else use generated random numbers { x = (-1.0) + 2 * ((double) rand() / RAND_MAX) ; // assign initial random number between -1 and 1 y = (-1.0) + 2 * ((double) rand() / RAND_MAX) ; // assign initial random number between -1 and 1 for(generated=0 ; generated < count ; generated++) { x_array[generated] = x ; y_array[generated] = y ; generator(&x, &y); } } else { while( 1 ) { # pragma omp critical { if( (generated - consumed) >= CHUNK_SIZE ) { start_index = consumed ; consumed = consumed + CHUNK_SIZE ; for( i=0 ; i 0) ) { break ; } } } #pragma omp barrier } //end pragma printf("%f\n", sum / count); return 0; }``````