.TH PCLASCL l "12 May 1997" "LAPACK version 1.5" "LAPACK auxiliary routine (version 1.5)"
.SH NAME
PCLASCL - multiplie the M-by-N complex distributed matrix sub( A ) denoting A(IA:IA+M-1,JA:JA+N-1) by the real scalar CTO/CFROM
.SH SYNOPSIS
.TP 20
SUBROUTINE PCLASCL(
TYPE, CFROM, CTO, M, N, A, IA, JA, DESCA,
INFO )
.TP 20
.ti +4
CHARACTER
TYPE
.TP 20
.ti +4
INTEGER
IA, INFO, JA, M, N
.TP 20
.ti +4
REAL
CFROM, CTO
.TP 20
.ti +4
INTEGER
DESCA( * )
.TP 20
.ti +4
COMPLEX
A( * )
.SH PURPOSE
PCLASCL multiplies the M-by-N complex distributed matrix sub( A )
denoting A(IA:IA+M-1,JA:JA+N-1) by the real scalar CTO/CFROM.  This
is done without over/underflow as long as the final result
CTO * A(I,J) / CFROM does not over/underflow. TYPE specifies that
sub( A ) may be full, upper triangular, lower triangular or upper
Hessenberg.
.br

Notes
.br
=====
.br

Each global data object is described by an associated description
vector.  This vector stores the information required to establish
the mapping between an object element and its corresponding process
and memory location.
.br

Let A be a generic term for any 2D block cyclicly distributed array.
Such a global array has an associated description vector DESCA.
In the following comments, the character _ should be read as
"of the global array".
.br

NOTATION        STORED IN      EXPLANATION
.br
--------------- -------------- --------------------------------------
DTYPE_A(global) DESCA( DTYPE_ )The descriptor type.  In this case,
                               DTYPE_A = 1.
.br
CTXT_A (global) DESCA( CTXT_ ) The BLACS context handle, indicating
                               the BLACS process grid A is distribu-
                               ted over. The context itself is glo-
                               bal, but the handle (the integer
                               value) may vary.
.br
M_A    (global) DESCA( M_ )    The number of rows in the global
                               array A.
.br
N_A    (global) DESCA( N_ )    The number of columns in the global
                               array A.
.br
MB_A   (global) DESCA( MB_ )   The blocking factor used to distribute
                               the rows of the array.
.br
NB_A   (global) DESCA( NB_ )   The blocking factor used to distribute
                               the columns of the array.
.br
RSRC_A (global) DESCA( RSRC_ ) The process row over which the first
                               row of the array A is distributed.
CSRC_A (global) DESCA( CSRC_ ) The process column over which the
                               first column of the array A is
                               distributed.
.br
LLD_A  (local)  DESCA( LLD_ )  The leading dimension of the local
                               array.  LLD_A >= MAX(1,LOCr(M_A)).

Let K be the number of rows or columns of a distributed matrix,
and assume that its process grid has dimension p x q.
.br
LOCr( K ) denotes the number of elements of K that a process
would receive if K were distributed over the p processes of its
process column.
.br
Similarly, LOCc( K ) denotes the number of elements of K that a
process would receive if K were distributed over the q processes of
its process row.
.br
The values of LOCr() and LOCc() may be determined via a call to the
ScaLAPACK tool function, NUMROC:
.br
        LOCr( M ) = NUMROC( M, MB_A, MYROW, RSRC_A, NPROW ),
        LOCc( N ) = NUMROC( N, NB_A, MYCOL, CSRC_A, NPCOL ).
An upper bound for these quantities may be computed by:
.br
        LOCr( M ) <= ceil( ceil(M/MB_A)/NPROW )*MB_A
.br
        LOCc( N ) <= ceil( ceil(N/NB_A)/NPCOL )*NB_A
.br

.SH ARGUMENTS
.TP 8
TYPE    (global input) CHARACTER
TYPE indices the storage type of the input distributed
matrix.
= 'G':  sub( A ) is a full matrix,
.br
= 'L':  sub( A ) is a lower triangular matrix,
.br
= 'U':  sub( A ) is an upper triangular matrix,
.br
= 'H':  sub( A ) is an upper Hessenberg matrix.
.TP 8
CFROM   (global input) REAL
CTO     (global input) REAL
The distributed matrix sub( A ) is multiplied by CTO/CFROM.
A(I,J) is computed without over/underflow if the final
result CTO * A(I,J) / CFROM can be represented without
over/underflow.  CFROM must be nonzero.
.TP 8
M       (global input) INTEGER
The number of rows to be operated on i.e the number of rows
of the distributed submatrix sub( A ). M >= 0.
.TP 8
N       (global input) INTEGER
The number of columns to be operated on i.e the number of
columns of the distributed submatrix sub( A ). N >= 0.
.TP 8
A       (local input/local output) COMPLEX pointer into the
local memory to an array of dimension (LLD_A,LOCc(JA+N-1)).
This array contains the local pieces of the distributed
matrix sub( A ). On exit, this array contains the local
pieces of the distributed matrix multiplied by CTO/CFROM.
.TP 8
IA      (global input) INTEGER
The row index in the global array A indicating the first
row of sub( A ).
.TP 8
JA      (global input) INTEGER
The column index in the global array A indicating the
first column of sub( A ).
.TP 8
DESCA   (global and local input) INTEGER array of dimension DLEN_.
The array descriptor for the distributed matrix A.
.TP 8
INFO    (local output) INTEGER
= 0:  successful exit
.br
< 0:  If the i-th argument is an array and the j-entry had
an illegal value, then INFO = -(i*100+j), if the i-th
argument is a scalar and had an illegal value, then
INFO = -i.
