collect_partialmap

subroutine collect_partialmap( pixelization, nmaps, mapnum, ncomp, first_pix, last_pix, submap, first_ring, last_ring, submap_size, local_map, myid, numprocs, root, comm)

Purpose:

Collects on a proc root part of a map made of submap_size consecutive pixels starting with pixel first_pix and including ncomp components, which are initially stored in the distributed form in local_map as a map number mapnum.

Parameters:

input:

pixelization-- [pixeltype], an S2HAT structure containing the info about the pixelization;

nmaps-- [integer(4b)], a total number of maps distributed over procs and stored in local_map;

mapnum-- [integer(4b)], a number of a map to be gathered on the proc root on the output;

ncomp-- [integer(4b)], a number of components per map(=1,2 or 3);

first_pix, last_pix-- [integer(8b)], a global number of the first and last pixel, respectively, to be collected;

first_ring, last_ring-- [integer(4b)], a number of a first and last ring, respectively, which define a distributed map (both included) to be stored on a given proc;

submap_size-- [integer(4b)], a number of pixels corresponding to a set of rings defined by first_ring and last_ring above;

local_map-- [real(dp)], an allocated pointer of a 3dim array of a size (0:submap_size-1,1:ncomp,1:nmaps) containing the ncomp component maps in the distributed form;

myid-- [integer(4b)], proc id (0,...,numprocs-1);

numprocs-- [integer(4b)], total number of procs used;

root-- [integer(4b)], defines a proc root on which the full map map is stored;

comm-- [integer(4b)], an mpi communicator for the numprocs procs.

output:

submap-- [real(dp)], an allocated pointer to a 2dim array of dimensions (0:last_pix-first_pix, 1:ncomp) storing a complete mapnum map on the proc root.

Comments:

On all the procs the input submaps, local_map, are assumed to be disjoint and composed of complete rings of both northern or southern hemispheres, with numbers in the range [first_ring, last_ring]. (Though that may lead to some extra memory overhead, especially for the scans confined fully to one or the other hemisphere, it does not affect the load_balancing and operation count. That may be corrected later.)