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DTBCON(1)		 LAPACK routine (version 3.2)		     DTBCON(1)

NAME
       DTBCON - estimates the reciprocal of the condition number of a triangu‐
       lar band matrix A, in either the 1-norm or the infinity-norm

SYNOPSIS
       SUBROUTINE DTBCON( NORM, UPLO, DIAG, N,	KD,  AB,  LDAB,	 RCOND,	 WORK,
			  IWORK, INFO )

	   CHARACTER	  DIAG, NORM, UPLO

	   INTEGER	  INFO, KD, LDAB, N

	   DOUBLE	  PRECISION RCOND

	   INTEGER	  IWORK( * )

	   DOUBLE	  PRECISION AB( LDAB, * ), WORK( * )

PURPOSE
       DTBCON estimates the reciprocal of the condition number of a triangular
       band matrix A, in either the 1-norm or the infinity-norm.  The norm  of
       A  is  computed	and an estimate is obtained for norm(inv(A)), then 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.

       UPLO    (input) CHARACTER*1
	       = 'U':  A is upper triangular;
	       = 'L':  A is lower triangular.

       DIAG    (input) CHARACTER*1
	       = 'N':  A is non-unit triangular;
	       = 'U':  A is unit triangular.

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

       KD      (input) INTEGER
	       The  number of superdiagonals or subdiagonals of the triangular
	       band matrix A.  KD >= 0.

       AB      (input) DOUBLE PRECISION array, dimension (LDAB,N)
	       The upper or lower triangular band  matrix  A,  stored  in  the
	       first kd+1 rows of the array. The j-th column of A is stored in
	       the j-th column of the array AB as  follows:  if	 UPLO  =  'U',
	       AB(kd+1+i-j,j)  =  A(i,j) for max(1,j-kd)<=i<=j; if UPLO = 'L',
	       AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd).  If DIAG =  'U',
	       the  diagonal  elements of A are not referenced and are assumed
	       to be 1.

       LDAB    (input) INTEGER
	       The leading dimension of the array AB.  LDAB >= KD+1.

       RCOND   (output) DOUBLE PRECISION
	       The reciprocal of the condition number of the  matrix  A,  com‐
	       puted as RCOND = 1/(norm(A) * norm(inv(A))).

       WORK    (workspace) DOUBLE PRECISION array, dimension (3*N)

       IWORK   (workspace) INTEGER array, dimension (N)

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

 LAPACK routine (version 3.2)	 November 2008			     DTBCON(1)
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