dppcon.f (3) Linux Manual Page

dppcon.f –

Synopsis

Functions/Subroutines

subroutine dppcon (UPLO, N, AP, ANORM, RCOND, WORK, IWORK, INFO)
DPPCON

Function/Subroutine Documentation

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

DPPCON

Purpose:

 DPPCON estimates the reciprocal of the condition number (in the

 1-norm) of a real symmetric positive definite packed matrix using

 the Cholesky factorization A = U**T*U or A = L*L**T computed by

 DPPTRF.

 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

 = ‘U’: Upper triangle of A is stored;

 = ‘L’: Lower triangle of A is stored.

N

 N is INTEGER

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

AP

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

 The triangular factor U or L from the Cholesky factorization

 A = U**T*U or A = L*L**T, packed columnwise in a linear

 array. The j-th column of U or L is stored in the array AP

 as follows:

 if UPLO = ‘U’, AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;

 if UPLO = ‘L’, AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.

ANORM

 ANORM is DOUBLE PRECISION

 The 1-norm (or infinity-norm) of the symmetric 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 (3*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 119 of file dppcon.f.

Author

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