SLANGT - return the value of the one norm, or the Frobe
nius norm, or the infinity norm, or the element of largest
absolute value of a real tridiagonal matrix A
SYNOPSIS
REAL FUNCTION SLANGT( NORM, N, DL, D, DU )
CHARACTER NORM
INTEGER N
REAL D( * ), DL( * ), DU( * )
PURPOSE
SLANGT 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
SLANGT returns the value
SLANGT = ( 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 Frobe
nius 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 SLANGT as
described above.
N (input) INTEGER
The order of the matrix A. N >= 0. When N = 0,
SLANGT is set to zero.
DL (input) REAL array, dimension (N-1)
The (n-1) sub-diagonal elements of A.
D (input) REAL array, dimension (N)
The diagonal elements of A.
The (n-1) super-diagonal elements of A.
Man(1) output converted with
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