Recursive Halving and Doubling To illustrate recursive halving and doubling suppose you have a vector distributed among p processors, and you need the sum of all components of the vector in each processor, i.e a sum reduction One method is to use a tree-based algorithm to compute the sum to a single processor and then broadcast the sum to every processorRecursive Halving and Doubling • To illustrate recursive halving and doubling, suppose you have a vector distributed among p processors, and you need the sum of all components of the vector in each processor, i.e., a sum reduction. • One method is to use a tree-based algorithm to compute the sum to a single processor and then broadcast the sum to every processor