dlansy.f man page

dlansy.f

Synopsis

Functions/Subroutines

double precision function dlansy (NORM, UPLO, N, A, LDA, WORK)
DLANSY returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric matrix.

Function/Subroutine Documentation

double precision function dlansy (character NORM, character UPLO, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( * ) WORK)

DLANSY returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric matrix.

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.
Returns:

DLANSY

DLANSY = ( 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 DLANSY as described
above.

UPLO

UPLO is 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
= 'L':  Lower triangular part of A is referenced

N

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

A

A is 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.

LDA

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

WORK

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

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

December 2016

Definition at line 124 of file dlansy.f.

Author

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Referenced By

The man page dlansy(3) is an alias of dlansy.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK