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RedHat 9 (Linux i386) - man page for dlangt (redhat section l)

DLANGT(l)					)					DLANGT(l)

NAME
       DLANGT - return the value of the one norm, or the Frobenius norm, or the infinity norm, or
       the element of largest absolute value of a real tridiagonal matrix A

SYNOPSIS
       DOUBLE PRECISION FUNCTION DLANGT( NORM, N, DL, D, DU )

	   CHARACTER	NORM

	   INTEGER	N

	   DOUBLE	PRECISION D( * ), DL( * ), DU( * )

PURPOSE
       DLANGT returns the value of the one norm, or the Frobenius norm, or the infinity norm,  or
       the element of largest absolute value of a real tridiagonal matrix A.

DESCRIPTION
       DLANGT returns the value

	  DLANGT = ( 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 DLANGT as described above.

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

       DL      (input) DOUBLE PRECISION array, dimension (N-1)
	       The (n-1) sub-diagonal elements of A.

       D       (input) DOUBLE PRECISION array, dimension (N)
	       The diagonal elements of A.

       DU      (input) DOUBLE PRECISION array, dimension (N-1)
	       The (n-1) super-diagonal elements of A.

LAPACK version 3.0			   15 June 2000 				DLANGT(l)


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