SLANGE - 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 matrix A
SYNOPSIS
REAL FUNCTION SLANGE( NORM, M, N, A, LDA, WORK )
CHARACTER NORM
INTEGER LDA, M, N
REAL A( LDA, * ), WORK( * )
PURPOSE
SLANGE 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
SLANGE returns the value
SLANGE = ( 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 SLANGE as
described above.
M (input) INTEGER
The number of rows of the matrix A. M >= 0. When
M = 0, SLANGE is set to zero.
N (input) INTEGER
The number of columns of the matrix A. N >= 0.
When N = 0, SLANGE is set to zero.
A (input) REAL array, dimension (LDA,N)
The m by n matrix A.
The leading dimension of the array A. LDA >=
max(M,1).
WORK (workspace) REAL array, dimension (LWORK),
where LWORK >= M when NORM = 'I'; otherwise, WORK
is not referenced.
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