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

292 HP MLIB User’s Guide

SSYRK/DSYRK/CHERK/CSYRK/ZHERK/ZSYRK Rank-k update

ldc The leading dimension of array c as declared in the

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

Output c The upper or lower triangle of the updated C matrix, as

speciﬁed by uplo, replaces the upper or lower triangle

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

unchanged.

Notes These subprograms conform to speciﬁcations of the Level 3 BLAS.

If an error in the arguments is detected, the subprograms call error handler

XERBLA, which writes an error message onto the standard error ﬁle and

terminates execution. The standard version of XERBLA (refer to the end of this

chapter) can be replaced with a user-supplied version to change the error

procedure. Error conditions are:

uplo ≠ ’L’ or ’l’ or ’U’ or ’u’

trans ≠ ’N’ or ’n’ or ’T’ or ’t’ or ’C’ or ’c’

n < 0

k < 0

lda too small

ldc < max(m,1)

Also, some values of trans listed above are invalid in subprograms CHERK,

CSYRK, ZHERK, and ZSYRK.

Actual character arguments in a subroutine call can be longer than the

corresponding dummy arguments. Therefore, readability of the CALL

statement may be improved, for example, by coding the uplo argument as

’LOWER’ for ’L’ or ’UPPER’ for ’U’. Refer to “Example 2.”