DLARHS
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
November 2006
November 2006
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 ) may be A or A' (transpose of A).
up the right hand sides for the linear system
op( A ) * X = B,
where op( A ) may be A or A' (transpose of A).
Arguments
| PATH |
(input) 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 |
(input) 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 |
(input) 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 |
(input) CHARACTER*1
Specifies the operation applied to the matrix A.
= 'N': System is A * x = b = 'T': System is A'* x = b = 'C': System is A'* x = b |
| M |
(input) INTEGER
The number or rows of the matrix A. M >= 0.
|
| N |
(input) INTEGER
The number of columns of the matrix A. N >= 0.
|
| KL |
(input) 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 |
(input) 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 |
(input) INTEGER
The number of right hand side vectors in the system A*X = B.
|
| A |
(input) DOUBLE PRECISION array, dimension (LDA,N)
The test matrix whose type is given by PATH.
|
| LDA |
(input) 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 |
(input 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 |
(input) INTEGER
The leading dimension of the array X. If TRANS = 'N',
LDX >= max(1,N); if TRANS = 'T', LDX >= max(1,M). |
| B |
(output) 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 |
(input) INTEGER
The leading dimension of the array B. If TRANS = 'N',
LDB >= max(1,M); if TRANS = 'T', LDB >= max(1,N). |
| ISEED |
(input/output) INTEGER array, dimension (4)
The seed vector for the random number generator (used in
DLATMS). Modified on exit. |
| INFO |
(output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value |