HP MLIB User's Guide Vol. 2 7th Ed.

Chapter 10 Introduction to ScaLAPACK 713
ScaLAPACK arguments
Table 10-10 Content of the Array Descriptor for Right-Hand-Side Dense Matrices
for Narrow Band and Tridiagonal Solvers
Array descriptor for out-of-core dense matrices
The array descriptor DESC_ is an integer array of length 11. It is used for the
ScaLAPACK routines involved in the out-of-core solution of dense linear
systems using LU, QR, or Cholesky factorizations. The matrix stored on disk is
composed of records. Each record corresponds to an MMB x NNB
DESC_(DTYPE_)=1 ScaLAPACK matrix and these records are organized in a
column major (Fortran array) manner. The array descriptor for out-of-core
matrices has extra fields to store file parameters associated with the matrix,
such as the I/O device unit number, MMB and NNB, and the amount of
temporary buffer storage available.
DESC_( )
Symbolic
Name
Scope Definition
1 DTYPE_B (global)
The descriptor type (DTYPE_B=502) for P
r
x
1 process grid for block-row distributed
matrices
2 CTXT_B (global)
The BLACS context handle, indicating the
BLACS process grid over which the global
matrix B is distributed. The context itself is
global, but the handle (the integer value)
may vary.
3 M_B (global) The number of rows in the global matrix B
4 MB_B (global) The row block size
5 RSRC_B (global)
The process row over which the first row of
the global matrix B is distributed.
6 LLD_B (local)
The leading dimension of the local array. For
tridiagonal subroutines, this entry is
ignored.
7 Unused, reserved.