DLANGE(3F)DLANGE(3F)NAME
DLANGE - 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 matrix
A
SYNOPSIS
DOUBLE PRECISION FUNCTION DLANGE( NORM, M, N, A, LDA, WORK )
CHARACTER NORM
INTEGER LDA, M, N
DOUBLE PRECISION A( LDA, * ), WORK( * )
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.
DESCRIPTION
DLANGE returns the value
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 matrix norm.
ARGUMENTS
NORM (input) CHARACTER*1
Specifies the value to be returned in DLANGE as described above.
M (input) INTEGER
The number of rows of the matrix A. M >= 0. When M = 0, DLANGE
is set to zero.
N (input) INTEGER
The number of columns of the matrix A. N >= 0. When N = 0,
DLANGE is set to zero.
A (input) DOUBLE PRECISION array, dimension (LDA,N)
The m by n matrix A.
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DLANGE(3F)DLANGE(3F)
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(M,1).
WORK (workspace) DOUBLE PRECISION array, dimension (LWORK),
where LWORK >= M when NORM = 'I'; otherwise, WORK is not
referenced.
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