Implementation of routines for butterfly-like communication scheme, with classic pair wise butterfly scheme. More...

Functions
int	truebutterfly_init (int indices, int count, int R, int nR, int *S, int nS, int *com_indices, int com_count, int steps, MPI_Comm comm)
	Initialize tables for butterfly-like communication scheme (true means pair wise) This routine set up needed tables for the butterfly communication scheme. Sending and receiving tabs should be well allocated(at least size of number of steps in butterfly scheme). Double pointer are partially allocated, the last allocation is performed inside the routine. com_indices and com_count are also allocated inside the routine, thus they are passing by reference. They represent indices which have to be communicated an their number. Algotithm is based 2 parts. The first one identify intersection between processors indices, using 3 successives butterfly communication schemes : bottom up, top down, and top down again. The second part works locally to build sets of indices to communicate.
double	truebutterfly_reduce (int *R, int nR, int nRmax, int *S, int nS, int nSmax, double *val, int steps, MPI_Comm comm)
	Perform a sparse sum reduction (or mapped reduction) using a butterfly-like communication scheme.

Detailed Description

Implementation of routines for butterfly-like communication scheme, with classic pair wise butterfly scheme.

Note:: Copyright (c) 2010-2012 APC CNRS Université Paris Diderot. This program is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see http://www.gnu.org/licenses/lgpl.html; For more information about ANR MIDAS'09 project see http://www.apc.univ-paris7.fr/APC_CS/Recherche/Adamis/MIDAS09/index.html; ACKNOWLEDGMENT: This work has been supported in part by the French National Research Agency (ANR) through COSINUS program (project MIDAS no. ANR-09-COSI-009).

Definition in file truebutterfly.c.

Functions