TESTING/LIN/sppt01.f(3) Library Functions Manual TESTING/LIN/sppt01.f(3)

TESTING/LIN/sppt01.f


subroutine sppt01 (uplo, n, a, afac, rwork, resid)
SPPT01

SPPT01

Purpose:

 SPPT01 reconstructs a symmetric 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.

Parameters

UPLO
          UPLO is CHARACTER*1
          Specifies whether the upper or lower triangular part of the
          symmetric 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 REAL array, dimension (N*(N+1)/2)
          The original symmetric matrix A, stored as a packed
          triangular matrix.

AFAC

          AFAC is REAL 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 REAL array, dimension (N)

RESID

          RESID is REAL
          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 92 of file sppt01.f.

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