zppt01.f - Man Page

subroutine zppt01 (uplo, n, a, afac, rwork, resid)
ZPPT01

ZPPT01

Purpose:

 ZPPT01 reconstructs a Hermitian positive definite packed matrix A
 from its L*L' or U'*U factorization and computes the residual
    norm( L*L' - A ) / ( N * norm(A) * EPS ) or
    norm( U'*U - A ) / ( N * norm(A) * EPS ),
 where EPS is the machine epsilon, L' is the conjugate transpose of
 L, and U' is the conjugate transpose of U.

Parameters

UPLO

          UPLO is CHARACTER*1
          Specifies whether the upper or lower triangular part of the
          Hermitian matrix A is stored:
          = 'U':  Upper triangular
          = 'L':  Lower triangular

N

          N is INTEGER
          The number of rows and columns of the matrix A.  N >= 0.

A

          A is COMPLEX*16 array, dimension (N*(N+1)/2)
          The original Hermitian matrix A, stored as a packed
          triangular matrix.

AFAC

          AFAC is COMPLEX*16 array, dimension (N*(N+1)/2)
          On entry, the factor L or U from the L*L' or U'*U
          factorization of A, stored as a packed triangular matrix.
          Overwritten with the reconstructed matrix, and then with the
          difference L*L' - A (or U'*U - A).

RWORK

          RWORK is DOUBLE PRECISION array, dimension (N)

RESID

          RESID is DOUBLE PRECISION
          If UPLO = 'L', norm(L*L' - A) / ( N * norm(A) * EPS )
          If UPLO = 'U', norm(U'*U - A) / ( N * norm(A) * EPS )

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 94 of file zppt01.f.