Node / RFnexus / code.git / files / exclusive_reduce.hh

Displaying Raw • Download

/*

Reduce N times while excluding ith input element

Copyright 2018 Ahmet Inan <inan@aicodix.de>

*/

#pragma once

namespace CODE {

template <typename TYPE, typename OPERATOR>

void exclusive_reduce(const TYPE *in, TYPE *out, int N, OPERATOR op)

{

TYPE pre = in[0];

for (int i = 1; i < N-1; ++i) {

out[i] = pre;

pre = op(pre, in[i]);

}

out[N-1] = pre;

TYPE suf = in[N-1];

for (int i = N-2; i > 0; --i) {

out[i] = op(out[i], suf);

suf = op(suf, in[i]);

}

out[0] = suf;

}

}