LAPACK 3.11.0
LAPACK: Linear Algebra PACKage

◆ dpot01()

subroutine dpot01 ( character  UPLO,
integer  N,
double precision, dimension( lda, * )  A,
integer  LDA,
double precision, dimension( ldafac, * )  AFAC,
integer  LDAFAC,
double precision, dimension( * )  RWORK,
double precision  RESID 
)

DPOT01

Purpose:
 DPOT01 reconstructs a symmetric positive definite 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
[in]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
[in]N
          N is INTEGER
          The number of rows and columns of the matrix A.  N >= 0.
[in]A
          A is DOUBLE PRECISION array, dimension (LDA,N)
          The original symmetric matrix A.
[in]LDA
          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,N)
[in,out]AFAC
          AFAC is DOUBLE PRECISION array, dimension (LDAFAC,N)
          On entry, the factor L or U from the L * L**T or U**T * U
          factorization of A.
          Overwritten with the reconstructed matrix, and then with
          the difference L * L**T - A (or U**T * U - A).
[in]LDAFAC
          LDAFAC is INTEGER
          The leading dimension of the array AFAC.  LDAFAC >= max(1,N).
[out]RWORK
          RWORK is DOUBLE PRECISION array, dimension (N)
[out]RESID
          RESID is DOUBLE PRECISION
          If UPLO = 'L', norm(L * L**T - A) / ( N * norm(A) * EPS )
          If UPLO = 'U', norm(U**T * U - A) / ( N * norm(A) * EPS )
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.