dsycon(3P) Sun Performance Library dsycon(3P)NAMEdsycon - estimate the reciprocal of the condition number (in the
1-norm) of a real symmetric matrix A using the factorization A =
U*D*U**T or A = L*D*L**T computed by DSYTRF
SYNOPSIS
SUBROUTINE DSYCON(UPLO, N, A, LDA, IPIVOT, ANORM, RCOND, WORK,
IWORK2, INFO)
CHARACTER * 1 UPLO
INTEGER N, LDA, INFO
INTEGER IPIVOT(*), IWORK2(*)
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION A(LDA,*), WORK(*)
SUBROUTINE DSYCON_64(UPLO, N, A, LDA, IPIVOT, ANORM, RCOND, WORK,
IWORK2, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, LDA, INFO
INTEGER*8 IPIVOT(*), IWORK2(*)
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION A(LDA,*), WORK(*)
F95 INTERFACE
SUBROUTINE SYCON(UPLO, [N], A, [LDA], IPIVOT, ANORM, RCOND, [WORK],
[IWORK2], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, LDA, INFO
INTEGER, DIMENSION(:) :: IPIVOT, IWORK2
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE SYCON_64(UPLO, [N], A, [LDA], IPIVOT, ANORM, RCOND, [WORK],
[IWORK2], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, LDA, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT, IWORK2
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void dsycon(char uplo, int n, double *a, int lda, int *ipivot, double
anorm, double *rcond, int *info);
void dsycon_64(char uplo, long n, double *a, long lda, long *ipivot,
double anorm, double *rcond, long *info);
PURPOSEdsycon estimates the reciprocal of the condition number (in the 1-norm)
of a real symmetric matrix A using the factorization A = U*D*U**T or A
= L*D*L**T computed by DSYTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
ARGUMENTS
UPLO (input)
Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix. = 'U': Upper trian‐
gular, form is A = U*D*U**T;
= 'L': Lower triangular, form is A = L*D*L**T.
N (input) The order of the matrix A. N >= 0.
A (input) The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by DSYTRF.
LDA (input)
The leading dimension of the array A. LDA >= max(1,N).
IPIVOT (input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D as
determined by DSYTRF.
ANORM (input)
The 1-norm of the original matrix A.
RCOND (output)
The reciprocal of the condition number of the matrix A, com‐
puted as RCOND = 1/(ANORM * AINVNM), where AINVNM is an esti‐
mate of the 1-norm of inv(A) computed in this routine.
WORK (workspace)
dimension(2*N)
IWORK2 (workspace) INTEGER array, dimension (N)
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
6 Mar 2009 dsycon(3P)
