LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
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stpt01.f File Reference

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Functions/Subroutines

subroutine stpt01 (UPLO, DIAG, N, AP, AINVP, RCOND, WORK, RESID)
 STPT01 More...
 

Function/Subroutine Documentation

subroutine stpt01 ( character  UPLO,
character  DIAG,
integer  N,
real, dimension( * )  AP,
real, dimension( * )  AINVP,
real  RCOND,
real, dimension( * )  WORK,
real  RESID 
)

STPT01

Purpose:
 STPT01 computes the residual for a triangular matrix A times its
 inverse when A is stored in packed format:
    RESID = norm(A*AINV - I) / ( N * norm(A) * norm(AINV) * EPS ),
 where EPS is the machine epsilon.
Parameters
[in]UPLO
          UPLO is CHARACTER*1
          Specifies whether the matrix A is upper or lower triangular.
          = 'U':  Upper triangular
          = 'L':  Lower triangular
[in]DIAG
          DIAG is CHARACTER*1
          Specifies whether or not the matrix A is unit triangular.
          = 'N':  Non-unit triangular
          = 'U':  Unit triangular
[in]N
          N is INTEGER
          The order of the matrix A.  N >= 0.
[in]AP
          AP is REAL array, dimension (N*(N+1)/2)
          The original upper or lower triangular matrix A, packed
          columnwise in a linear array.  The j-th column of A is stored
          in the array AP as follows:
          if UPLO = 'U', AP((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;
          if UPLO = 'L',
             AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=n.
[in,out]AINVP
          AINVP is REAL array, dimension (N*(N+1)/2)
          On entry, the (triangular) inverse of the matrix A, packed
          columnwise in a linear array as in AP.
          On exit, the contents of AINVP are destroyed.
[out]RCOND
          RCOND is REAL
          The reciprocal condition number of A, computed as
          1/(norm(A) * norm(AINV)).
[out]WORK
          WORK is REAL array, dimension (N)
[out]RESID
          RESID is REAL
          norm(A*AINV - I) / ( N * norm(A) * norm(AINV) * EPS )
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
November 2011

Definition at line 109 of file stpt01.f.

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