dppcon (l)  Linux Manuals
dppcon: estimates the reciprocal of the condition number (in the 1norm) of a real symmetric positive definite packed matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPPTRF
Command to display dppcon
manual in Linux: $ man l dppcon
NAME
DPPCON  estimates the reciprocal of the condition number (in the 1norm) of a real symmetric positive definite packed matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPPTRF
SYNOPSIS
 SUBROUTINE DPPCON(

UPLO, N, AP, ANORM, RCOND, WORK, IWORK, INFO )

CHARACTER
UPLO

INTEGER
INFO, N

DOUBLE
PRECISION ANORM, RCOND

INTEGER
IWORK( * )

DOUBLE
PRECISION AP( * ), WORK( * )
PURPOSE
DPPCON estimates the reciprocal of the condition number (in the
1norm) 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))).
ARGUMENTS
 UPLO (input) CHARACTER*1

= aqUaq: Upper triangle of A is stored;
= aqLaq: Lower triangle of A is stored.
 N (input) INTEGER

The order of the matrix A. N >= 0.
 AP (input) 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 jth column of U or L is stored in the array AP
as follows:
if UPLO = aqUaq, AP(i + (j1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = aqLaq, AP(i + (j1)*(2nj)/2) = L(i,j) for j<=i<=n.
 ANORM (input) DOUBLE PRECISION

The 1norm (or infinitynorm) of the symmetric matrix A.
 RCOND (output) 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 1norm of inv(A) computed in this routine.
 WORK (workspace) DOUBLE PRECISION array, dimension (3*N)

 IWORK (workspace) INTEGER array, dimension (N)

 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
Pages related to dppcon
 dppcon (3)
 dppequ (l)  computes row and column scalings intended to equilibrate a symmetric positive definite matrix A in packed storage and reduce its condition number (with respect to the twonorm)
 dpprfs (l)  improves the computed solution to a system of linear equations when the coefficient matrix is symmetric positive definite and packed, and provides error bounds and backward error estimates for the solution
 dppsv (l)  computes the solution to a real system of linear equations A * X = B,
 dppsvx (l)  uses the Cholesky factorization A = U**T*U or A = L*L**T to compute the solution to a real system of linear equations A * X = B,
 dpptrf (l)  computes the Cholesky factorization of a real symmetric positive definite matrix A stored in packed format
 dpptri (l)  computes the inverse of a real symmetric positive definite matrix A using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPPTRF
 dpptrs (l)  solves a system of linear equations A*X = B with a symmetric positive definite matrix A in packed storage using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPPTRF