dspcon(3P) Sun Performance Library dspcon(3P)NAMEdspcon - estimate the reciprocal of the condition number (in the
1-norm) of a real symmetric packed matrix A using the factorization A =
U*D*U**T or A = L*D*L**T computed by DSPTRF
SYNOPSIS
SUBROUTINE DSPCON(UPLO, N, A, IPIVOT, ANORM, RCOND, WORK, IWORK2,
INFO)
CHARACTER * 1 UPLO
INTEGER N, INFO
INTEGER IPIVOT(*), IWORK2(*)
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION A(*), WORK(*)
SUBROUTINE DSPCON_64(UPLO, N, A, IPIVOT, ANORM, RCOND, WORK, IWORK2,
INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, INFO
INTEGER*8 IPIVOT(*), IWORK2(*)
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION A(*), WORK(*)
F95 INTERFACE
SUBROUTINE SPCON(UPLO, [N], A, IPIVOT, ANORM, RCOND, [WORK], [IWORK2],
[INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, INFO
INTEGER, DIMENSION(:) :: IPIVOT, IWORK2
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: A, WORK
SUBROUTINE SPCON_64(UPLO, [N], A, IPIVOT, ANORM, RCOND, [WORK],
[IWORK2], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT, IWORK2
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: A, WORK
C INTERFACE
#include <sunperf.h>
void dspcon(char uplo, int n, double *a, int *ipivot, double anorm,
double *rcond, int *info);
void dspcon_64(char uplo, long n, double *a, long *ipivot, double
anorm, double *rcond, long *info);
PURPOSEdspcon estimates the reciprocal of the condition number (in the 1-norm)
of a real symmetric packed matrix A using the factorization A =
U*D*U**T or A = L*D*L**T computed by DSPTRF.
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) Double precision array, dimension (N*(N+1)/2) The block diag‐
onal matrix D and the multipliers used to obtain the factor U
or L as computed by DSPTRF, stored as a packed triangular
matrix.
IPIVOT (input)
Integer array, dimension (N) Details of the interchanges and
the block structure of D as determined by DSPTRF.
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)
Double precision array, 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 dspcon(3P)
