CXML
        	    
LAPACK version 3.0
cgbcon(3)

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

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

      CHARACTER	     NORM

      INTEGER	     INFO, KL, KU, LDAB, N

      REAL	     ANORM, RCOND

      INTEGER	     IPIV( * )

      REAL	     RWORK( * )

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

DESCRIPTION
  CGBCON 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 CGBTRF.

  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 array, dimension (LDAB,N)
	  Details of the LU factorization of the band matrix A, as computed
	  by CGBTRF.  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) REAL
	  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) REAL
	  The reciprocal of the condition number of the matrix A, computed as
	  RCOND = 1/(norm(A) * norm(inv(A))).

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

  RWORK	  (workspace) REAL array, dimension (N)

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