# thrust/thrust

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 #include #include #include #include #include // This example shows how to compute a bounding box // for a set of points in two dimensions. struct point2d { float x, y; __host__ __device__ point2d() : x(0), y(0) {} __host__ __device__ point2d(float _x, float _y) : x(_x), y(_y) {} }; // bounding box type typedef thrust::pair bbox; // reduce a pair of bounding boxes (a,b) to a bounding box containing a and b struct bbox_reduction : public thrust::binary_function { __host__ __device__ bbox operator()(bbox a, bbox b) { // lower left corner point2d ll(thrust::min(a.first.x, b.first.x), thrust::min(a.first.y, b.first.y)); // upper right corner point2d ur(thrust::max(a.second.x, b.second.x), thrust::max(a.second.y, b.second.y)); return bbox(ll, ur); } }; // convert a point to a bbox containing that point, (point) -> (point, point) struct bbox_transformation : public thrust::unary_function { __host__ __device__ bbox operator()(point2d point) { return bbox(point, point); } }; int main(void) { const size_t N = 40; thrust::default_random_engine rng; thrust::uniform_real_distribution u01(0.0f, 1.0f); // allocate storage for points thrust::device_vector points(N); // generate some random points in the unit square for(size_t i = 0; i < N; i++) { float x = u01(rng); float y = u01(rng); points[i] = point2d(x,y); } // initial bounding box contains first point bbox init = bbox(points[0], points[0]); // transformation operation bbox_transformation unary_op; // binary reduction operation bbox_reduction binary_op; // compute the bounding box for the point set bbox result = thrust::transform_reduce(points.begin(), points.end(), unary_op, init, binary_op); // print output std::cout << "bounding box " << std::fixed; std::cout << "(" << result.first.x << "," << result.first.y << ") "; std::cout << "(" << result.second.x << "," << result.second.y << ")" << std::endl; return 0; }
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