Tutorial by Examples

h = 1.0 / n; #pragma omp parallel for private(x) shared(n, h) reduction(+:area) for (i = 1; i <= n; i++) { x = h * (i - 0.5); area += (4.0 / (1.0 + x*x)); } pi = h * area; In this example, each threads execute a subset of the iteration count. Each thread has its local private copy ...

h = 1.0 / n; #pragma omp parallel for private(x) shared(n, h, area) for (i = 1; i <= n; i++) { x = h * (i - 0.5); #pragma omp critical { area += (4.0 / (1.0 + x*x)); } } pi = h * area; In this example, each threads execute a subset of the iteration count and they accumul...

h = 1.0 / n; #pragma omp parallel for private(x) shared(n, h, area) for (i = 1; i <= n; i++) { x = h * (i - 0.5); #pragma atomic area += (4.0 / (1.0 + x*x)); } pi = h * area; In this example, each threads execute a subset of the iteration count and they accumulate atomically int...

h = 1.0 / n; #pragma omp parallel private(x) shared(n, h) { double thread_area = 0; // Private / local variable #pragma omp for for (i = 1; i <= n; i++) { x = h * (i - 0.5); thread_area += (4.0 / (1.0 + x*x)); } #pragma omp atomic ...