DLANST(l) ) DLANST(l)NAME
DLANST - 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
symmetric tridiagonal matrix A
SYNOPSIS
DOUBLE PRECISION FUNCTION DLANST( NORM, N, D, E )
CHARACTER NORM
INTEGER N
DOUBLE PRECISION D( * ), E( * )
PURPOSE
DLANST 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 sym‐
metric tridiagonal matrix A.
DESCRIPTION
DLANST returns the value
DLANST = ( 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 DLANST as described
above.
N (input) INTEGER
The order of the matrix A. N >= 0. When N = 0, DLANST is set
to zero.
D (input) DOUBLE PRECISION array, dimension (N)
The diagonal elements of A.
E (input) DOUBLE PRECISION array, dimension (N-1)
The (n-1) sub-diagonal or super-diagonal elements of A.
LAPACK version 3.0 15 June 2000 DLANST(l)
