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

710 HP MLIB LAPACK User’s Guide
ScaLAPACK arguments
UPLO Used by the Hermitian, symmetric, and triangular
distributed matrix routines to specify whether the
upper or lower triangle is being referenced.
U - Upper triangle.
L - Lower triangle.
DIAG Used by the triangular distributed matrix routines to
specify whether the distributed matrix is unit
triangular.
U - Unit triangular.
R - Non-unit triangular.
When DIAG is supplied as ‘U’ the diagonal elements
are not referenced.
The corresponding lower-case characters may be supplied (with the same
meaning) but any other value is illegal.
A longer character string can be passed as the actual argument, making the
calling program more readable, but only the first character is significant. (This
is a standard feature of Fortran 77.)
Problem dimensions
The problem dimensions may be passed as zero, in which case the computation
(or part of it) is skipped. Negative dimensions are regarded as erroneous.
Array descriptors
An array descriptor is associated with each global array. This array stores the
information required to establish the mapping between each global array entry
and its corresponding process and memory location. The notations x_ used in
the entries of the array descriptor denote the attributes of a global array. For
example, M_ denotes the number of rows and M_A specifically denotes the
number of rows in global matrix A. These descriptors assume different storage
for the global data. The length of the array descriptor is specified by DLEN_ and
varies according to the descriptor type DTYPE_.
Array descriptors are provided for:
• Dense matrices
• Band and tridiagonal matrices
• Out-of-core matrices