# dlarhs.f - Man Page

TESTING/LIN/dlarhs.f

## Synopsis

### Functions/Subroutines

subroutine dlarhs (path, xtype, uplo, trans, m, n, kl, ku, nrhs, a, lda, x, ldx, b, ldb, iseed, info)
DLARHS

## Function/Subroutine Documentation

### subroutine dlarhs (character*3 path, character xtype, character uplo, character trans, integer m, integer n, integer kl, integer ku, integer nrhs, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldx, * ) x, integer ldx, double precision, dimension( ldb, * ) b, integer ldb, integer, dimension( 4 ) iseed, integer info)

DLARHS

Purpose:

DLARHS chooses a set of NRHS random solution vectors and sets
up the right hand sides for the linear system
op(A) * X = B,
where op(A) = A or A**T, depending on TRANS.
Parameters

PATH

PATH is CHARACTER*3
The type of the real matrix A.  PATH may be given in any
combination of upper and lower case.  Valid types include
xGE:  General m x n matrix
xGB:  General banded matrix
xPO:  Symmetric positive definite, 2-D storage
xPP:  Symmetric positive definite packed
xPB:  Symmetric positive definite banded
xSY:  Symmetric indefinite, 2-D storage
xSP:  Symmetric indefinite packed
xSB:  Symmetric indefinite banded
xTR:  Triangular
xTP:  Triangular packed
xTB:  Triangular banded
xQR:  General m x n matrix
xLQ:  General m x n matrix
xQL:  General m x n matrix
xRQ:  General m x n matrix
where the leading character indicates the precision.

XTYPE

XTYPE is CHARACTER*1
Specifies how the exact solution X will be determined:
= 'N':  New solution; generate a random X.
= 'C':  Computed; use value of X on entry.

UPLO

UPLO is CHARACTER*1
Specifies whether the upper or lower triangular part of the
matrix A is stored, if A is symmetric.
= 'U':  Upper triangular
= 'L':  Lower triangular

TRANS

TRANS is CHARACTER*1
Used only if A is nonsymmetric; specifies the operation
applied to the matrix A.
= 'N':  B := A    * X  (No transpose)
= 'T':  B := A**T * X  (Transpose)
= 'C':  B := A**H * X  (Conjugate transpose = Transpose)

M

M is INTEGER
The number or rows of the matrix A.  M >= 0.

N

N is INTEGER
The number of columns of the matrix A.  N >= 0.

KL

KL is INTEGER
Used only if A is a band matrix; specifies the number of
subdiagonals of A if A is a general band matrix or if A is
symmetric or triangular and UPLO = 'L'; specifies the number
of superdiagonals of A if A is symmetric or triangular and
UPLO = 'U'.  0 <= KL <= M-1.

KU

KU is INTEGER
Used only if A is a general band matrix or if A is
triangular.

If PATH = xGB, specifies the number of superdiagonals of A,
and 0 <= KU <= N-1.

If PATH = xTR, xTP, or xTB, specifies whether or not the
matrix has unit diagonal:
= 1:  matrix has non-unit diagonal (default)
= 2:  matrix has unit diagonal

NRHS

NRHS is INTEGER
The number of right hand side vectors in the system A*X = B.

A

A is DOUBLE PRECISION array, dimension (LDA,N)
The test matrix whose type is given by PATH.

LDA

LDA is INTEGER
The leading dimension of the array A.
If PATH = xGB, LDA >= KL+KU+1.
If PATH = xPB, xSB, xHB, or xTB, LDA >= KL+1.
Otherwise, LDA >= max(1,M).

X

X is or output) DOUBLE PRECISION array, dimension(LDX,NRHS)
On entry, if XTYPE = 'C' (for 'Computed'), then X contains
the exact solution to the system of linear equations.
On exit, if XTYPE = 'N' (for 'New'), then X is initialized
with random values.

LDX

LDX is INTEGER
The leading dimension of the array X.  If TRANS = 'N',
LDX >= max(1,N); if TRANS = 'T', LDX >= max(1,M).

B

B is DOUBLE PRECISION array, dimension (LDB,NRHS)
The right hand side vector(s) for the system of equations,
computed from B = op(A) * X, where op(A) is determined by
TRANS.

LDB

LDB is INTEGER
The leading dimension of the array B.  If TRANS = 'N',
LDB >= max(1,M); if TRANS = 'T', LDB >= max(1,N).

ISEED

ISEED is INTEGER array, dimension (4)
The seed vector for the random number generator (used in
DLATMS).  Modified on exit.

INFO

INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 203 of file dlarhs.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dlarhs(3) is an alias of dlarhs.f(3).

Tue Nov 28 2023 12:08:43 Version 3.12.0 LAPACK