zpbt02.f3
Usage
Functions/Subroutines
subroutine zpbt02 (uplo, n, kd, nrhs, a, lda, x, ldx, b, ldb, rwork, resid)
ZPBT02
Function/Subroutine Documentation
subroutine zpbt02 (character uplo, integer n, integer kd, integer nrhs, complex*16, dimension( lda, * ) a, integer lda, complex*16, dimension( ldx, * ) x, integer ldx, complex*16, dimension( ldb, * ) b, integer ldb, double precision, dimension( * ) rwork, double precision resid)
ZPBT02
Purpose:
!> !> ZPBT02 computes the residual for a solution of a Hermitian banded !> system of equations A*x = b: !> RESID = norm( B - A*X ) / ( norm(A) * norm(X) * EPS) !> where EPS is the machine precision. !>
Parameters
UPLO
!> UPLO is CHARACTER*1 !> Specifies whether the upper or lower triangular part of the !> Hermitian 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. !>
KD
!> KD is INTEGER !> The number of super-diagonals of the matrix A if UPLO = 'U', !> or the number of sub-diagonals if UPLO = 'L'. KD >= 0. !>
NRHS
!> NRHS is INTEGER !> The number of right hand sides. NRHS >= 0. !>
A
!> A is COMPLEX*16 array, dimension (LDA,N) !> The original Hermitian band matrix A. If UPLO = 'U', the !> upper triangular part of A is stored as a band matrix; if !> UPLO = 'L', the lower triangular part of A is stored. The !> columns of the appropriate triangle are stored in the columns !> of A and the diagonals of the triangle are stored in the rows !> of A. See ZPBTRF for further details. !>
LDA
!> LDA is INTEGER. !> The leading dimension of the array A. LDA >= max(1,KD+1). !>
X
!> X is COMPLEX*16 array, dimension (LDX,NRHS) !> The computed solution vectors for the system of linear !> equations. !>
LDX
!> LDX is INTEGER !> The leading dimension of the array X. LDX >= max(1,N). !>
B
!> B is COMPLEX*16 array, dimension (LDB,NRHS) !> On entry, the right hand side vectors for the system of !> linear equations. !> On exit, B is overwritten with the difference B - A*X. !>
LDB
!> LDB is INTEGER !> The leading dimension of the array B. LDB >= max(1,N). !>
RWORK
!> RWORK is DOUBLE PRECISION array, dimension (N) !>
RESID
!> RESID is DOUBLE PRECISION !> The maximum over the number of right hand sides of !> norm(B - A*X) / ( norm(A) * norm(X) * EPS ). !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 134 of file zpbt02.f.