sgbcon
sgbcon - estimate the reciprocal of the condition number of a real general band matrix A, in either the 1-norm or the infinity-norm,
SUBROUTINE SGBCON( NORM, N, NSUB, NSUPER, A, LDA, IPIVOT, ANORM,
* RCOND, WORK, WORK2, INFO)
CHARACTER * 1 NORM
INTEGER N, NSUB, NSUPER, LDA, INFO
INTEGER IPIVOT(*), WORK2(*)
REAL ANORM, RCOND
REAL A(LDA,*), WORK(*)
SUBROUTINE SGBCON_64( NORM, N, NSUB, NSUPER, A, LDA, IPIVOT, ANORM,
* RCOND, WORK, WORK2, INFO)
CHARACTER * 1 NORM
INTEGER*8 N, NSUB, NSUPER, LDA, INFO
INTEGER*8 IPIVOT(*), WORK2(*)
REAL ANORM, RCOND
REAL A(LDA,*), WORK(*)
SUBROUTINE GBCON( NORM, [N], NSUB, NSUPER, A, [LDA], IPIVOT, ANORM,
* RCOND, [WORK], [WORK2], [INFO])
CHARACTER(LEN=1) :: NORM
INTEGER :: N, NSUB, NSUPER, LDA, INFO
INTEGER, DIMENSION(:) :: IPIVOT, WORK2
REAL :: ANORM, RCOND
REAL, DIMENSION(:) :: WORK
REAL, DIMENSION(:,:) :: A
SUBROUTINE GBCON_64( NORM, [N], NSUB, NSUPER, A, [LDA], IPIVOT,
* ANORM, RCOND, [WORK], [WORK2], [INFO])
CHARACTER(LEN=1) :: NORM
INTEGER(8) :: N, NSUB, NSUPER, LDA, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT, WORK2
REAL :: ANORM, RCOND
REAL, DIMENSION(:) :: WORK
REAL, DIMENSION(:,:) :: A
#include <sunperf.h>
void sgbcon(char norm, int n, int nsub, int nsuper, float *a, int lda, int *ipivot, float anorm, float *rcond, int *info);
void sgbcon_64(char norm, long n, long nsub, long nsuper, float *a, long lda, long *ipivot, float anorm, float *rcond, long *info);
sgbcon estimates the reciprocal of the condition number of a real
general band matrix A, in either the 1-norm or the infinity-norm,
using the LU factorization computed by SGBTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as
RCOND = 1 / ( norm(A) * norm(inv(A)) ).
-
* NORM (input)
-
Specifies whether the 1-norm condition number or the
infinity-norm condition number is required:
-
* N (input)
-
The order of the matrix A. N >= 0.
-
* NSUB (input)
-
The number of subdiagonals within the band of A. NSUB >= 0.
-
* NSUPER (input)
-
The number of superdiagonals within the band of A. NSUPER >= 0.
-
* A (input)
-
Details of the LU factorization of the band matrix A, as
computed by SGBTRF. U is stored as an upper triangular band
matrix with NSUB+NSUPER superdiagonals in rows 1 to NSUB+NSUPER+1, and
the multipliers used during the factorization are stored in
rows NSUB+NSUPER+2 to 2*NSUB+NSUPER+1.
-
* LDA (input)
-
The leading dimension of the array A. LDA >= 2*NSUB+NSUPER+1.
-
* IPIVOT (input)
-
The pivot indices; for 1 <= i <= N, row i of the matrix was
interchanged with row IPIVOT(i).
-
* ANORM (input)
-
If NORM = '1' or 'O', the 1-norm of the original matrix A.
If NORM = 'I', the infinity-norm of the original matrix A.
-
* RCOND (output)
-
The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(norm(A) * norm(inv(A))).
-
* WORK (workspace)
-
dimension(2*N)
-
* WORK2 (workspace)
-
-
* INFO (output)
-