ssycon

NAME

ssycon - 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 SSYTRF

SYNOPSIS

  SUBROUTINE SSYCON( UPLO, N, A, LDA, IPIVOT, ANORM, RCOND, WORK, 
 *      IWORK2, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, LDA, INFO
  INTEGER IPIVOT(*), IWORK2(*)
  REAL ANORM, RCOND
  REAL A(LDA,*), WORK(*)
 
  SUBROUTINE SSYCON_64( UPLO, N, A, LDA, IPIVOT, ANORM, RCOND, WORK, 
 *      IWORK2, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, LDA, INFO
  INTEGER*8 IPIVOT(*), IWORK2(*)
  REAL ANORM, RCOND
  REAL 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 :: ANORM, RCOND
  REAL, DIMENSION(:) :: WORK
  REAL, 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 :: ANORM, RCOND
  REAL, DIMENSION(:) :: WORK
  REAL, DIMENSION(:,:) :: A

C INTERFACE

#include <sunperf.h>

void ssycon(char uplo, int n, float *a, int lda, int *ipivot, float anorm, float *rcond, int *info);

void ssycon_64(char uplo, long n, float *a, long lda, long *ipivot, float anorm, float *rcond, long *info);

PURPOSE

ssycon 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 SSYTRF.

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.
* 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 SSYTRF.
* LDA (input): The leading dimension of the array A. LDA >= max(1,N).
* IPIVOT (input): Details of the interchanges and the block structure of D as determined by SSYTRF.
* ANORM (input): The 1-norm of the original matrix A.
* RCOND (output): The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an estimate of the 1-norm of inv(A) computed in this routine.
* WORK (workspace): dimension(2*N)
* IWORK2 (workspace)
* INFO (output)