HP MLIB User's Guide Vol. 1 7th Ed.

Chapter 4 Sparse BLAS Operations 497
Diagonal matrix-matrix multiply SDIAMM/DDIAMM/CDIAMM/ZDIAMM
Name SDIAMM/DDIAMM/CDIAMM/ZDIAMM
Diagonal matrix-matrix multiply
Purpose Diagonal matrix-matrix multiply. These subprograms compute the
matrix-matrix product AB, where A is a m-by-k sparse matrix, and B is a k-by-n
matrix. Optionally, A may be replaced by A
T
or A*, where A
T
or A* is a k-by-m
matrix, and B is a m-by-n matrix. Here A
T
is the transpose and A* is the
conjugate-transpose of A. The product may be stored in the result matrix C or
optionally may be added to or subtracted from it. This is handled in a
convenient, but general way by two scalar arguments, α and β, which are used
as multipliers of the matrix product and the result matrix. Specifically, these
subprograms compute matrix products of the form
Usage VECLIB:
SUBROUTINE SDIAMM
INTEGER*4 transa, m, n, k, lda, ndiag, ldb, ldc, lwork
INTEGER*4 descra(*), idiag(*)
REAL*4 alpha, beta
REAL*4 val(*), b(ldb,*), c(ldc,*), work(*)
CALL SDIAMM (transa, m, n, k, alpha, descra, val, lda, idiag, ndiag, b,
ldb, beta, c, ldc, work, lwork)
SUBROUTINE DDIAMM
INTEGER*4 transa, m, n, k, lda, ndiag, ldb, ldc, lwork
INTEGER*4 descra(*), idiag(*)
REAL*8 alpha, beta
REAL*8 val(*), b(ldb,*), c(ldc,*), work(*)
CALL DDIAMM (transa, m, n, k, alpha, descra, val, lda, idiag, ndiag, b,
ldb, beta, c, ldc, work, lwork)
SUBROUTINE CDIAMM
INTEGER*4 transa, m, n, k, lda, ndiag, ldb, ldc, lwork
INTEGER*4 descra(*), idiag(*)
COMPLEX*8 alpha, beta
COMPLEX*8 val(*), b(ldb,*), c(ldc,*), work(*)
CALL CDIAMM (transa, m, n, k, alpha, descra, val, lda, idiag, ndiag, b,
ldb, beta, c, ldc, work, lwork)
C ←αAB +βC
C ←αA
T
B +βC
C ←αA
∗
B +βC