Rank-1 update

 

 

SSYR/DSYR/CHER/ZHER

 

 

incx > 0

x is stored forward in array x; that is,

 

 

 

xi is stored in x((i−1)⋅incx+1).

 

 

incx < 0

x is stored backward in array x; that

 

 

 

is, xi is stored in x((i−n)⋅incx+1).

 

 

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

 

 

array x, that is, if xi 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.

 

Chapter 3 Basic Matrix Operations 277