clangt-f(3)

clangt.f –

Synopsis

Functions/Subroutines

REAL function clangt (NORM, N, DL, D, DU)
CLANGT 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

REAL function clangt (characterNORM, integerN, complex, dimension( * )DL, complex, dimension( * )D, complex, dimension( * )DU)

CLANGT 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:

 CLANGT returns the value of the one norm, or the Frobenius norm, or
 the infinity norm, or the element of largest absolute value of a
 complex tridiagonal matrix A.

Returns:

CLANGT

 CLANGT = ( 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 CLANGT as described
 above.

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

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

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

 DU is COMPLEX 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 clangt.f.

Author

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