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.TH DLANSY l "15 June 2000" "LAPACK version 3.0" ")"
.SH NAME
DLANSY - 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 symmetric matrix A
.SH SYNOPSIS
.TP 17
DOUBLE PRECISION
FUNCTION DLANSY( NORM, UPLO, N, A, LDA, WORK )
.TP 17
.ti +4
CHARACTER
NORM, UPLO
.TP 17
.ti +4
INTEGER
LDA, N
.TP 17
.ti +4
DOUBLE
PRECISION A( LDA, * ), WORK( * )
.SH PURPOSE
DLANSY 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 symmetric matrix A.
.SH DESCRIPTION
DLANSY returns the value
.br
DLANSY = ( max(abs(A(i,j))), NORM = 'M' or 'm'
.br
(
.br
( norm1(A), NORM = '1', 'O' or 'o'
.br
(
.br
( normI(A), NORM = 'I' or 'i'
.br
(
.br
( 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.
.SH ARGUMENTS
.TP 8
NORM (input) CHARACTER*1
Specifies the value to be returned in DLANSY as described
above.
.TP 8
UPLO (input) CHARACTER*1
Specifies whether the upper or lower triangular part of the
symmetric matrix A is to be referenced.
= 'U': Upper triangular part of A is referenced
.br
= 'L': Lower triangular part of A is referenced
.TP 8
N (input) INTEGER
The order of the matrix A. N >= 0. When N = 0, DLANSY is
set to zero.
.TP 8
A (input) DOUBLE PRECISION array, dimension (LDA,N)
The symmetric matrix A. If UPLO = 'U', the leading n by n
upper triangular part of A contains the upper triangular part
of the matrix A, and the strictly lower triangular part of A
is not referenced. If UPLO = 'L', the leading n by n lower
triangular part of A contains the lower triangular part of
the matrix A, and the strictly upper triangular part of A is
not referenced.
.TP 8
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(N,1).
.TP 8
WORK (workspace) DOUBLE PRECISION array, dimension (LWORK),
where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise,
WORK is not referenced.
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