# dlansp.f man page

dlansp.f

## Synopsis

### Functions/Subroutines

double precision function dlansp (NORM, UPLO, N, AP, WORK)
DLANSP returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a symmetric matrix supplied in packed form.

## Function/Subroutine Documentation

### double precision function dlansp (character NORM, character UPLO, integer N, double precision, dimension( * ) AP, double precision, dimension( * ) WORK)

DLANSP returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a symmetric matrix supplied in packed form.

Purpose:

``` DLANSP  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,  supplied in packed form.```
Returns:

DLANSP

```    DLANSP = ( 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 DLANSP as described
above.```

UPLO

```          UPLO is CHARACTER*1
Specifies whether the upper or lower triangular part of the
symmetric matrix A is supplied.
= 'U':  Upper triangular part of A is supplied
= 'L':  Lower triangular part of A is supplied```

N

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

AP

```          AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
The upper or lower triangle of the symmetric matrix A, packed
columnwise in a linear array.  The j-th column of A is stored
in the array AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.```

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 116 of file dlansp.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Tue Nov 14 2017 Version 3.8.0 LAPACK