TESTING/LIN/strt01.f(3) Library Functions Manual TESTING/LIN/strt01.f(3)

TESTING/LIN/strt01.f


subroutine strt01 (uplo, diag, n, a, lda, ainv, ldainv, rcond, work, resid)
STRT01

STRT01

Purpose:

!>
!> STRT01 computes the residual for a triangular matrix A times its
!> inverse:
!>    RESID = norm( A*AINV - I ) / ( N * norm(A) * norm(AINV) * EPS ),
!> where EPS is the machine epsilon.
!> 

Parameters

UPLO
!>          UPLO is CHARACTER*1
!>          Specifies whether the matrix A is upper or lower triangular.
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!> 

DIAG

!>          DIAG is CHARACTER*1
!>          Specifies whether or not the matrix A is unit triangular.
!>          = 'N':  Non-unit triangular
!>          = 'U':  Unit triangular
!> 

N

!>          N is INTEGER
!>          The order of the matrix A.  N >= 0.
!> 

A

!>          A is REAL array, dimension (LDA,N)
!>          The triangular matrix A.  If UPLO = 'U', the leading n by n
!>          upper triangular part of the array A contains the upper
!>          triangular matrix, and the strictly lower triangular part of
!>          A is not referenced.  If UPLO = 'L', the leading n by n lower
!>          triangular part of the array A contains the lower triangular
!>          matrix, and the strictly upper triangular part of A is not
!>          referenced.  If DIAG = 'U', the diagonal elements of A are
!>          also not referenced and are assumed to be 1.
!> 

LDA

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

AINV

!>          AINV is REAL array, dimension (LDAINV,N)
!>          On entry, the (triangular) inverse of the matrix A, in the
!>          same storage format as A.
!>          On exit, the contents of AINV are destroyed.
!> 

LDAINV

!>          LDAINV is INTEGER
!>          The leading dimension of the array AINV.  LDAINV >= max(1,N).
!> 

RCOND

!>          RCOND is REAL
!>          The reciprocal condition number of A, computed as
!>          1/(norm(A) * norm(AINV)).
!> 

WORK

!>          WORK is REAL array, dimension (N)
!> 

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.

Definition at line 122 of file strt01.f.

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