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, and
- out-of-core matrices

**Table 4.2:** Valid values of DESC_(DTYPE_)

Tue May 13 09:21:01 EDT 1997