dlangt.f man page

dlangt.f —

Synopsis

Functions/Subroutines

DOUBLE PRECISION function dlangt (NORM, N, DL, D, DU)
DLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix.

Function/Subroutine Documentation

DOUBLE PRECISION function dlangt (characterNORM, integerN, double precision, dimension( * )DL, double precision, dimension( * )D, double precision, dimension( * )DU)

DLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix.

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.

Returns:

DLANGT

   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 consistent matrix norm.

Parameters:

NORM

NORM is CHARACTER*1
Specifies the value to be returned in DLANGT as described
above.

N

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

DL

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

D

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

DU

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

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 107 of file dlangt.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

dlangt(3) is an alias of dlangt.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK