SUBROUTINE ZGBCON( NORM, N, NSUB, NSUPER, A, LDA, IPIVOT, ANORM, * RCOND, WORK, WORK2, INFO) CHARACTER * 1 NORM DOUBLE COMPLEX A(LDA,*), WORK(*) INTEGER N, NSUB, NSUPER, LDA, INFO INTEGER IPIVOT(*) DOUBLE PRECISION ANORM, RCOND DOUBLE PRECISION WORK2(*) SUBROUTINE ZGBCON_64( NORM, N, NSUB, NSUPER, A, LDA, IPIVOT, ANORM, * RCOND, WORK, WORK2, INFO) CHARACTER * 1 NORM DOUBLE COMPLEX A(LDA,*), WORK(*) INTEGER*8 N, NSUB, NSUPER, LDA, INFO INTEGER*8 IPIVOT(*) DOUBLE PRECISION ANORM, RCOND DOUBLE PRECISION WORK2(*)
SUBROUTINE GBCON( NORM, [N], NSUB, NSUPER, A, [LDA], IPIVOT, ANORM, * RCOND, [WORK], [WORK2], [INFO]) CHARACTER(LEN=1) :: NORM COMPLEX(8), DIMENSION(:) :: WORK COMPLEX(8), DIMENSION(:,:) :: A INTEGER :: N, NSUB, NSUPER, LDA, INFO INTEGER, DIMENSION(:) :: IPIVOT REAL(8) :: ANORM, RCOND REAL(8), DIMENSION(:) :: WORK2 SUBROUTINE GBCON_64( NORM, [N], NSUB, NSUPER, A, [LDA], IPIVOT, * ANORM, RCOND, [WORK], [WORK2], [INFO]) CHARACTER(LEN=1) :: NORM COMPLEX(8), DIMENSION(:) :: WORK COMPLEX(8), DIMENSION(:,:) :: A INTEGER(8) :: N, NSUB, NSUPER, LDA, INFO INTEGER(8), DIMENSION(:) :: IPIVOT REAL(8) :: ANORM, RCOND REAL(8), DIMENSION(:) :: WORK2
void zgbcon(char norm, int n, int nsub, int nsuper, doublecomplex *a, int lda, int *ipivot, double anorm, double *rcond, int *info);
void zgbcon_64(char norm, long n, long nsub, long nsuper, doublecomplex *a, long lda, long *ipivot, double anorm, double *rcond, long *info);
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)) ).