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Argument Descriptions for Band and Tridiagonal Routines

           

All ScaLAPACK narrow band and tridiagonal routines assume that the global matrices are distributed in a one-dimensional block data distribution. Thus, each process has at most one block of data. With selective choices for the block size NB_ and the order N_ of the global matrix, it is possible that some processes in the process grid may not receive any data, or the last process receiving data will receive a smaller block of data than the other processes.

For further information on one-dimensional block-column or block-row data distribution, please refer to section 4.4.1.

The description of a block-column distributed band matrix consists of (N, A, JA, DESCA)

The description of a block-row distributed right-hand-side matrix consists of (NRHS, B, IB, DESCB)

The description of a block-distributed diagonally dominant-like tridiagonal matrix consists of (N, DL, D, DU, JA, DESCA)

The description of a block-distributed symmetric positive definite tridiagonal matrix consists of (N, D, E, JA, DESCA)

The name of the row or column index for the global array has the form I<array_name>  or J<array_name> , respectively. The array descriptor has a name of the form DESC<array_name> .    The length of the array descriptor is specified by DLEN_ and varies according to the descriptor type DTYPE_.

Included in the leading comments of each subroutine (immediately preceding the Argument section), is a brief note describing the array descriptor    and some commonly used expressions in calculating workspace.

The style of the argument  descriptions for symmetric positive definite narrow band routines (PxPByyy) and diagonally dominant-like narrow band routines (PxDByyy) is illustrated by the following example:

The style of the argument  descriptions for diagonally dominant-like tridiagonal routines (PxDTyyy) is illustrated by the following example:

The style of the argument  descriptions for symmetric positive definite tridiagonal routines (PxPTyyy) is illustrated by the following example:

The description of each argument contains the following information:


next up previous contents index
Next: Matrix Storage Conventions for Up: In-Core Narrow Band and Previous: Array Descriptor for the

Susan Blackford
Tue May 13 09:21:01 EDT 1997