LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
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subroutine zlaqhp | ( | character | UPLO, |
integer | N, | ||
complex*16, dimension( * ) | AP, | ||
double precision, dimension( * ) | S, | ||
double precision | SCOND, | ||
double precision | AMAX, | ||
character | EQUED | ||
) |
ZLAQHP scales a Hermitian matrix stored in packed form.
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ZLAQHP equilibrates a Hermitian matrix A using the scaling factors in the vector S.
[in] | UPLO | UPLO is CHARACTER*1 Specifies whether the upper or lower triangular part of the Hermitian matrix A is stored. = 'U': Upper triangular = 'L': Lower triangular |
[in] | N | N is INTEGER The order of the matrix A. N >= 0. |
[in,out] | AP | AP is COMPLEX*16 array, dimension (N*(N+1)/2) On entry, the upper or lower triangle of the Hermitian matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. On exit, the equilibrated matrix: diag(S) * A * diag(S), in the same storage format as A. |
[in] | S | S is DOUBLE PRECISION array, dimension (N) The scale factors for A. |
[in] | SCOND | SCOND is DOUBLE PRECISION Ratio of the smallest S(i) to the largest S(i). |
[in] | AMAX | AMAX is DOUBLE PRECISION Absolute value of largest matrix entry. |
[out] | EQUED | EQUED is CHARACTER*1 Specifies whether or not equilibration was done. = 'N': No equilibration. = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S). |
THRESH is a threshold value used to decide if scaling should be done based on the ratio of the scaling factors. If SCOND < THRESH, scaling is done. LARGE and SMALL are threshold values used to decide if scaling should be done based on the absolute size of the largest matrix element. If AMAX > LARGE or AMAX < SMALL, scaling is done.
Definition at line 128 of file zlaqhp.f.