SPOT01 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.

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 (LDA,N)


          The original symmetric matrix A.

LDA

          LDA is INTEGER


          The leading dimension of the array A.  LDA >= max(1,N)

AFAC

          AFAC is REAL 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).

LDAFAC

          LDAFAC is INTEGER


          The leading dimension of the array AFAC.  LDAFAC >= max(1,N).

RWORK

          RWORK is REAL array, dimension (N)

RESID

          RESID is REAL


          If UPLO = 'L', norm(L * L**T - A) / ( N * norm(A) * EPS )


          If UPLO = 'U', norm(U**T * U - A) / ( N * norm(A) * EPS )

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

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