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

Chapter 3 Basic Matrix Operations 293
Rank-k update SSYRK/DSYRK/CHERK/CSYRK/ZHERK/ZSYRK
Example 1 Apply a REAL*4 rank-6 update AA
T
to an 8-by-8 real symmetric matrix C
whose upper triangle is stored in the upper triangle of an array C of dimension
10-by-10, where A is an 8-by-6 real matrix stored in an array A, also of
dimension 10-by-10.
CHARACTER*1 UPLO,TRANS
INTEGER*4 N,K,LDA,LDC
REAL*4 ALPHA,BETA,A(10,10),C(10,10)
UPLO = ’U’
TRANS = ’N’
N = 8
K = 6
ALPHA = 1.0
BETA = 1.0
LDA = 10
LDC = 10
CALL SSYRK (UPLO,TRANS,N,K,ALPHA,A,LDA,BETA,C,LDC)
Example 2 Apply a COMPLEX*8 Hermitian rank-2 update −2AA* to a 9-by-9 complex
Hermitian matrix C whose lower triangle is stored in the lower triangle of an
array C of dimension 10-by-10, where A is a 9-by-2 complex matrix stored in an
array A of dimension 10-by-10.
INTEGER*4 N,K,LDA,LDC
COMPLEX*8 A(10,10),C(10,10)
N = 9
K = 2
LDA = 10
LDC = 10
CALL CHERK (’LOWER’,’NONTRANS’,N,K,-2.0,A,LDA,1.0,C,LDC)