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

Chapter 10 Introduction to ScaLAPACK 709

ScaLAPACK arguments

ScaLAPACK routine arguments appear in the following order:

• Arguments specifying options

• Problem dimensions

• Array or scalar arguments deﬁning the input data (some of them may be

overwritten by results)

• Other array or scalar arguments returning results

• Work arrays (and associated array dimensions)

• Diagnostic argument INFO

Note that not every category is present in each of the routines.

When deﬁning each of these categories of arguments, ScaLAPACK

distinguishes between local and global data. On entry to a ScaLAPACK routine,

local input arguments may have different values on each process in the process

grid. Similarly, local output arguments may be assigned different values on

different processes in the process grid on exit from the ScaLAPACK routine.

Option arguments

Arguments specifying options are usually of type CHARACTER*1. The

arguments that specify options are character arguments with the names SIDE,

TRANS, UPLO, and DIAG. On entry to a ScaLAPACK routine, these arguments

are global input and must have the same value on each process in the process

grid.

SIDE L - Multiply general distributed matrix by symmetric

or triangular distributed matrix on the left.

R - Multiply general distributed matrix by symmetric

or triangular distributed matrix on the right.

TRANS N - Operate with the distributed matrix.

T - Operate with the transpose of the distributed

matrix.

C - Operate with the conjugate transpose of the

distributed matrix.

In the real case the values ‘T’ and ‘C’ have the same

meaning. In the complex case the value ‘T’ is not

allowed.