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dlange-f(3)

dlange.f –

Synopsis

Functions/Subroutines

DOUBLE PRECISION function dlange (NORM, M, N, A, LDA, WORK)
DLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general rectangular matrix.

Function/Subroutine Documentation

DOUBLE PRECISION function dlange (characterNORM, integerM, integerN, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )WORK)

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

Purpose:

 DLANGE 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 matrix A.

Returns:

DLANGE

 DLANGE = ( 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 DLANGE as described
 above.

M

 M is INTEGER
 The number of rows of the matrix A. M >= 0. When M = 0,
 DLANGE is set to zero.

N

 N is INTEGER
 The number of columns of the matrix A. N >= 0. When N = 0,
 DLANGE is set to zero.

A

 A is DOUBLE PRECISION array, dimension (LDA,N)
 The m by n matrix A.

LDA

 LDA is INTEGER
 The leading dimension of the array A. LDA >= max(M,1).

WORK

 WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)),
 where LWORK >= M when NORM = 'I'; otherwise, WORK is not
 referenced.

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 115 of file dlange.f.

Author

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