table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/LIN/spot05.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/LIN/spot05.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/TESTING/LIN/spot05.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine SPOT05 (uplo, n, nrhs, a, lda, b, ldb, x, ldx,
xact, ldxact, ferr, berr, reslts)
SPOT05
Function/Subroutine Documentation¶
subroutine SPOT05 (character uplo, integer n, integer nrhs, real, dimension( lda, * ) a, integer lda, real, dimension( ldb, * ) b, integer ldb, real, dimension( ldx, * ) x, integer ldx, real, dimension( ldxact, * ) xact, integer ldxact, real, dimension( * ) ferr, real, dimension( * ) berr, real, dimension( * ) reslts)¶
SPOT05
Purpose:
!> !> SPOT05 tests the error bounds from iterative refinement for the !> computed solution to a system of equations A*X = B, where A is a !> symmetric n by n matrix. !> !> RESLTS(1) = test of the error bound !> = norm(X - XACT) / ( norm(X) * FERR ) !> !> A large value is returned if this ratio is not less than one. !> !> RESLTS(2) = residual from the iterative refinement routine !> = the maximum of BERR / ( (n+1)*EPS + (*) ), where !> (*) = (n+1)*UNFL / (min_i (abs(A)*abs(X) +abs(b))_i ) !>
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 of the matrices X, B, and XACT, and the !> order of the matrix A. N >= 0. !>
NRHS
!> NRHS is INTEGER !> The number of columns of the matrices X, B, and XACT. !> NRHS >= 0. !>
A
!> A is REAL array, dimension (LDA,N) !> The symmetric matrix A. If UPLO = 'U', the leading n by n !> upper triangular part of A contains the upper triangular part !> of the matrix A, and the strictly lower triangular part of A !> is not referenced. If UPLO = 'L', the leading n by n lower !> triangular part of A contains the lower triangular part of !> the matrix A, and the strictly upper triangular part of A is !> not referenced. !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,N). !>
B
!> B is REAL array, dimension (LDB,NRHS) !> The right hand side vectors for the system of linear !> equations. !>
LDB
!> LDB is INTEGER !> The leading dimension of the array B. LDB >= max(1,N). !>
X
!> X is REAL array, dimension (LDX,NRHS) !> The computed solution vectors. Each vector is stored as a !> column of the matrix X. !>
LDX
!> LDX is INTEGER !> The leading dimension of the array X. LDX >= max(1,N). !>
XACT
!> XACT is REAL array, dimension (LDX,NRHS) !> The exact solution vectors. Each vector is stored as a !> column of the matrix XACT. !>
LDXACT
!> LDXACT is INTEGER !> The leading dimension of the array XACT. LDXACT >= max(1,N). !>
FERR
!> FERR is REAL array, dimension (NRHS) !> The estimated forward error bounds for each solution vector !> X. If XTRUE is the true solution, FERR bounds the magnitude !> of the largest entry in (X - XTRUE) divided by the magnitude !> of the largest entry in X. !>
BERR
!> BERR is REAL array, dimension (NRHS) !> The componentwise relative backward error of each solution !> vector (i.e., the smallest relative change in any entry of A !> or B that makes X an exact solution). !>
RESLTS
!> RESLTS is REAL array, dimension (2) !> The maximum over the NRHS solution vectors of the ratios: !> RESLTS(1) = norm(X - XACT) / ( norm(X) * FERR ) !> RESLTS(2) = BERR / ( (n+1)*EPS + (*) ) !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 162 of file spot05.f.
Author¶
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