dppcon(3)

dppcon3

Part of dppcon.f(3).

Usage

Functions/Subroutines

subroutine dppcon (uplo, n, ap, anorm, rcond, work, iwork, info)
DPPCON

Function/Subroutine Documentation

subroutine dppcon (character uplo, integer n, double precision, dimension( * ) ap, double precision anorm, double precision rcond, double precision, dimension( * ) work, integer, dimension( * ) iwork, integer info)

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.

Definition at line 117 of file dppcon.f.

Releases

14 releases since Debian 1.3 (Bo); the text changed 11 times.

  1. 1.3
  2. 2.0–2.2
  3. 3.0
  4. 3.1
  5. 4.0
  6. 7
  7. 8
  8. 9
  9. 10
  10. 11
  11. 12
  12. Arch

Author

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