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

Chapter 3 Basic Matrix Operations 277

Rank-1 update SSYR/DSYR/CHER/ZHER

incx > 0 x is stored forward in array x; that is,

is stored in x((i−1)×incx+1).

incx < 0 x is stored backward in array x; that

is, x

is stored in x((i−n)×incx+1).

Use incx = 1 if the vector x is stored contiguously in

array x, that is, if x

is stored in x(i). Refer to “BLAS

Indexing Conventions” in the introduction to

Chapter 2.

a Array whose upper or lower triangle, as speciﬁed by

uplo, contains the upper or lower triangle of an n-by-n

real symmetric or complex Hermitian matrix A. The

other triangle of a is not referenced.

lda The leading dimension of array a as declared in the

calling program unit, with lda ≥ max(n,1).

Output a The upper or lower triangle of the updated A matrix, as

speciﬁed by uplo, replaces the upper or lower triangle

of the input, respectively. The other triangle of a is

unchanged.