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LAPACK version 3.0
clantb(3)

PURPOSE
  CLANTB - return the value of the one norm, or the Frobenius norm, or the
  infinity norm, or the element of largest absolute value of an n by n
  triangular band matrix A, with ( k + 1 ) diagonals

SYNTAX
  REAL FUNCTION CLANTB( NORM, UPLO, DIAG, N, K, AB, LDAB, WORK )

      CHARACTER DIAG, NORM, UPLO

      INTEGER	K, LDAB, N

      REAL	WORK( * )

      COMPLEX	AB( LDAB, * )

DESCRIPTION
  CLANTB returns the value of the one norm, or the Frobenius norm, or the
  infinity norm, or the element of largest absolute value of an n by n
  triangular band matrix A, with ( k + 1 ) diagonals.

DESCRIPTION
  CLANTB returns the value

     CLANTB = ( max(abs(A(i,j))), NORM = 'M' or 'm'
	      (
	      ( norm1(A),	  NORM = '1', 'O' or 'o'
	      (
	      ( normI(A),	  NORM = 'I' or 'i'
	      (
	      ( normF(A),	  NORM = 'F', 'f', 'E' or 'e'

  where	 norm1	denotes the  one norm of a matrix (maximum column sum), normI
  denotes the  infinity norm  of a matrix  (maximum row sum) and normF
  denotes the  Frobenius norm of a matrix (square root of sum of squares).
  Note that  max(abs(A(i,j)))  is not a	 matrix norm.

ARGUMENTS
  NORM	  (input) CHARACTER*1
	  Specifies the value to be returned in CLANTB as described above.

  UPLO	  (input) CHARACTER*1
	  Specifies whether the matrix A is upper or lower triangular.	=
	  'U':	Upper triangular
	  = 'L':  Lower triangular

  DIAG	  (input) CHARACTER*1
	  Specifies whether or not the matrix A is unit triangular.  = 'N':
	  Non-unit triangular
	  = 'U':  Unit triangular

  N	  (input) INTEGER
	  The order of the matrix A.  N >= 0.  When N = 0, CLANTB is set to
	  zero.

  K	  (input) INTEGER
	  The number of super-diagonals of the matrix A if UPLO = 'U', or the
	  number of sub-diagonals of the matrix A if UPLO = 'L'.  K >= 0.

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

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

  WORK	  (workspace) REAL array, dimension (LWORK),
	  where LWORK >= N when NORM = 'I'; otherwise, WORK is not
	  referenced.