psb_scatter -- Scatter Global Dense Matrix

These subroutines scatters the portions of global dense matrix owned by a process to all the processes in the processes grid.

$$loc\_x_i \leftarrow scatter(glob\_x)$$

where:

$glob\_x$

is the global matrix $glob\_x_{1:m,1:n}$

$loc\_x_i$

is the local portion of global dense matrix on process $i$.

$scatter$

is the scatter function.

Table 16: Data types

$x_i, y$	Subroutine
Integer	psb_scatter
Short Precision Real	psb_scatter
Long Precision Real	psb_scatter
Short Precision Complex	psb_scatter
Long Precision Complex	psb_scatter

call psb_scatter(glob_x, loc_x, desc_a, info, root)
call psb_scatter(glob_x, loc_x, desc_a, info, root)

Type:

Synchronous.

On Entry

glob_x

The array that must be scattered into local pieces.
Scope: global
Type: required
Intent: in.
Specified as: a rank one or two array.

desc_a

contains data structures for communications.
Scope: local
Type: required
Intent: in.
Specified as: a structured data of type descdatapsb_desc_type.

root

The process that holds the global copy. If $root=-1$ all the processes have a copy of the global vector.
Scope: global
Type: optional
Intent: in.
Specified as: an integer variable $-1\le root\le np-1$, default $-1$.

On Return

loc_x

the local portion of global dense matrix $glob\_x$.
Scope: local
Type: required
Intent: out.
Specified as: a rank one or two array containing numbers of the type indicated in Table 16.

info

Error code.
Scope: local
Type: required
Intent: out.
An integer value; 0 means no error has been detected.