LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
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dptt01.f File Reference

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Functions/Subroutines

subroutine dptt01 (N, D, E, DF, EF, WORK, RESID)
 DPTT01 More...
 

Function/Subroutine Documentation

subroutine dptt01 ( integer  N,
double precision, dimension( * )  D,
double precision, dimension( * )  E,
double precision, dimension( * )  DF,
double precision, dimension( * )  EF,
double precision, dimension( * )  WORK,
double precision  RESID 
)

DPTT01

Purpose:
 DPTT01 reconstructs a tridiagonal matrix A from its L*D*L'
 factorization and computes the residual
    norm(L*D*L' - A) / ( n * norm(A) * EPS ),
 where EPS is the machine epsilon.
Parameters
[in]N
          N is INTEGTER
          The order of the matrix A.
[in]D
          D is DOUBLE PRECISION array, dimension (N)
          The n diagonal elements of the tridiagonal matrix A.
[in]E
          E is DOUBLE PRECISION array, dimension (N-1)
          The (n-1) subdiagonal elements of the tridiagonal matrix A.
[in]DF
          DF is DOUBLE PRECISION array, dimension (N)
          The n diagonal elements of the factor L from the L*D*L'
          factorization of A.
[in]EF
          EF is DOUBLE PRECISION array, dimension (N-1)
          The (n-1) subdiagonal elements of the factor L from the
          L*D*L' factorization of A.
[out]WORK
          WORK is DOUBLE PRECISION array, dimension (2*N)
[out]RESID
          RESID is DOUBLE PRECISION
          norm(L*D*L' - A) / (n * norm(A) * EPS)
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
November 2011

Definition at line 92 of file dptt01.f.

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