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NAME
     zgbcon - estimate the reciprocal of the condition number  of
     a complex general band matrix A, in either the 1-norm or the
     infinity-norm,

SYNOPSIS
     SUBROUTINE ZGBCON( NORM, N, KL, KU, AB, LDAB,  IPIV,  ANORM,
               RCOND, WORK, RWORK, INFO )

     CHARACTER NORM

     INTEGER INFO, KL, KU, LDAB, N

     DOUBLE PRECISION ANORM, RCOND

     INTEGER IPIV( * )

     DOUBLE PRECISION RWORK( * )

     COMPLEX*16 AB( LDAB, * ), WORK( * )



     #include <sunperf.h>

     void zgbcon(char norm, int n, int kl, int ku,  doublecomplex
               *zab,  int ldab, int *ipivot, double anorm, double
               *drcond, int *info) ;

PURPOSE
     ZGBCON estimates the reciprocal of the condition number of a
     complex  general  band matrix A, in either the 1-norm or the
     infinity-norm,  using  the  LU  factorization  computed   by
     ZGBTRF.

     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)) ).


ARGUMENTS
     NORM      (input) CHARACTER*1
               Specifies whether the 1-norm condition  number  or
               the infinity-norm condition number is required:
               = '1' or 'O':  1-norm;
               = 'I':         Infinity-norm.

     N         (input) INTEGER
               The order of the matrix A.  N >= 0.

     KL        (input) INTEGER
               The number of subdiagonals within the band  of  A.
               KL >= 0.

     KU        (input) INTEGER
               The number of superdiagonals within the band of A.
               KU >= 0.

     AB        (input) COMPLEX*16 array, dimension (LDAB,N)
               Details of the LU factorization of the band matrix
               A, as computed by ZGBTRF.  U is stored as an upper
               triangular band matrix with  KL+KU  superdiagonals
               in  rows  1  to  KL+KU+1, and the multipliers used
               during  the  factorization  are  stored  in   rows
               KL+KU+2 to 2*KL+KU+1.

     LDAB      (input) INTEGER
               The leading dimension of the array  AB.   LDAB  >=
               2*KL+KU+1.

     IPIV      (input) INTEGER array, dimension (N)
               The pivot indices; for 1 <= i <= N, row i  of  the
               matrix was interchanged with row IPIV(i).

     ANORM     (input) DOUBLE PRECISION
               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) DOUBLE PRECISION
               The reciprocal of  the  condition  number  of  the
               matrix   A,  computed  as  RCOND  =  1/(norm(A)  *
               norm(inv(A))).

     WORK      (workspace) COMPLEX*16 array, dimension (2*N)

     RWORK     (workspace) DOUBLE PRECISION array, dimension (N)

     INFO      (output) INTEGER
               = 0:  successful exit
               < 0: if INFO = -i, the i-th argument had an  ille-
               gal value

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