dspcon.f (3) Linux Manual Page

dspcon.f –

Synopsis

Functions/Subroutines

subroutine dspcon (UPLO, N, AP, IPIV, ANORM, RCOND, WORK, IWORK, INFO)
DSPCON

Function/Subroutine Documentation

subroutine dspcon (characterUPLO, integerN, double precision, dimension( * )AP, integer, dimension( * )IPIV, double precisionANORM, double precisionRCOND, double precision, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO)

DSPCON

Purpose:

 DSPCON estimates the reciprocal of the condition number (in the

 1-norm) of a real symmetric packed matrix A using the factorization

 A = U*D*U**T or A = L*D*L**T computed by DSPTRF.

 An estimate is obtained for norm(inv(A)), and the reciprocal of the

 condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).

 

Parameters:

UPLO

 UPLO is CHARACTER*1

 Specifies whether the details of the factorization are stored

 as an upper or lower triangular matrix.

 = ‘U’: Upper triangular, form is A = U*D*U**T;

 = ‘L’: Lower triangular, form is A = L*D*L**T.

N

 N is INTEGER

 The order of the matrix A. N >= 0.

AP

 AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)

 The block diagonal matrix D and the multipliers used to

 obtain the factor U or L as computed by DSPTRF, stored as a

 packed triangular matrix.

IPIV

 IPIV is INTEGER array, dimension (N)

 Details of the interchanges and the block structure of D

 as determined by DSPTRF.

ANORM

 ANORM is DOUBLE PRECISION

 The 1-norm of the original matrix A.

RCOND

 RCOND is DOUBLE PRECISION

 The reciprocal of the condition number of the matrix A,

 computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an

 estimate of the 1-norm of inv(A) computed in this routine.

WORK

 WORK is DOUBLE PRECISION array, dimension (2*N)

IWORK

 IWORK is INTEGER array, dimension (N)

INFO

 INFO is INTEGER

 = 0: successful exit

 < 0: if INFO = -i, the i-th argument had an illegal value

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 125 of file dspcon.f.

Author

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