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

Chapter 10 Introduction to ScaLAPACK 711
ScaLAPACK arguments
Array descriptors are differentiated by the DTYPE_ entry in the descriptor. At
the present time, the following values of DESC_(DTYPE_) are valid.
Table 10-7 Valid Values of DESC_(DTYPE_)
Array descriptor for in-core dense matrices
The array descriptor DESC_ is an integer array of length 9. It is used for the
ScaLAPACK routines solving dense linear systems and eigenvalue problems.
All global vector and matrix operands are assumed to be distributed on the
process grid according to the one- or two-dimensional block cyclic data
distribution scheme.
Table 10-8 Content of the Array Descriptor for In-Core Dense Matrices
DESC_(DTYPE_) Designation
1 dense matrices
501 narrow band and tridiagonal coefficient matrices
502 narrow band and tridiagonal right-hand-side matrices
601 out-of-core dense matrices
DESC_( ) Symbolic
Name
Scope Definition
1 DTYPE_A (global)
Descriptor type DTYPE_A=1 for dense
matrices.
2 CTXT_A (global)
BLACS context handle, indicating the
BLACS process grid over which the global
matrix A is distributed. The context itself
is global, but the handle (the integer
value) may vary.
3 M_A (global) Number of rows in the global array A.
4 N_A (global) Number of columns in the global array A.
5 MB_A (global)
Blocking factor used to distribute the rows
of the array.
6 NB_A (global)
Blocking factor used to distribute the
columns of the array.
7 RSRC_A (global)
Process row over which the first row of the
array A is distributed.
8 CSRC_A (global)
Process column over which the first
column of array A is distributed.
9 LLD_A (local) Leading dimension of the local array.