org.netlib.lapack
Class SGELS
java.lang.Object
org.netlib.lapack.SGELS
public class SGELS
- extends java.lang.Object
SGELS is a simplified interface to the JLAPACK routine sgels.
This interface converts Java-style 2D row-major arrays into
the 1D column-major linearized arrays expected by the lower
level JLAPACK routines. Using this interface also allows you
to omit offset and leading dimension arguments. However, because
of these conversions, these routines will be slower than the low
level ones. Following is the description from the original Fortran
source. Contact seymour@cs.utk.edu with any questions.
* ..
*
* Purpose
* =======
*
* SGELS solves overdetermined or underdetermined real linear systems
* involving an M-by-N matrix A, or its transpose, using a QR or LQ
* factorization of A. It is assumed that A has full rank.
*
* The following options are provided:
*
* 1. If TRANS = 'N' and m >= n: find the least squares solution of
* an overdetermined system, i.e., solve the least squares problem
* minimize || B - A*X ||.
*
* 2. If TRANS = 'N' and m < n: find the minimum norm solution of
* an underdetermined system A * X = B.
*
* 3. If TRANS = 'T' and m >= n: find the minimum norm solution of
* an undetermined system A**T * X = B.
*
* 4. If TRANS = 'T' and m < n: find the least squares solution of
* an overdetermined system, i.e., solve the least squares problem
* minimize || B - A**T * X ||.
*
* Several right hand side vectors b and solution vectors x can be
* handled in a single call; they are stored as the columns of the
* M-by-NRHS right hand side matrix B and the N-by-NRHS solution
* matrix X.
*
* Arguments
* =========
*
* TRANS (input) CHARACTER
* = 'N': the linear system involves A;
* = 'T': the linear system involves A**T.
*
* M (input) INTEGER
* The number of rows of the matrix A. M >= 0.
*
* N (input) INTEGER
* The number of columns of the matrix A. N >= 0.
*
* NRHS (input) INTEGER
* The number of right hand sides, i.e., the number of
* columns of the matrices B and X. NRHS >=0.
*
* A (input/output) REAL array, dimension (LDA,N)
* On entry, the M-by-N matrix A.
* On exit,
* if M >= N, A is overwritten by details of its QR
* factorization as returned by SGEQRF;
* if M < N, A is overwritten by details of its LQ
* factorization as returned by SGELQF.
*
* LDA (input) INTEGER
* The leading dimension of the array A. LDA >= max(1,M).
*
* B (input/output) REAL array, dimension (LDB,NRHS)
* On entry, the matrix B of right hand side vectors, stored
* columnwise; B is M-by-NRHS if TRANS = 'N', or N-by-NRHS
* if TRANS = 'T'.
* On exit, B is overwritten by the solution vectors, stored
* columnwise:
* if TRANS = 'N' and m >= n, rows 1 to n of B contain the least
* squares solution vectors; the residual sum of squares for the
* solution in each column is given by the sum of squares of
* elements N+1 to M in that column;
* if TRANS = 'N' and m < n, rows 1 to N of B contain the
* minimum norm solution vectors;
* if TRANS = 'T' and m >= n, rows 1 to M of B contain the
* minimum norm solution vectors;
* if TRANS = 'T' and m < n, rows 1 to M of B contain the
* least squares solution vectors; the residual sum of squares
* for the solution in each column is given by the sum of
* squares of elements M+1 to N in that column.
*
* LDB (input) INTEGER
* The leading dimension of the array B. LDB >= MAX(1,M,N).
*
* WORK (workspace/output) REAL array, dimension (LWORK)
* On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*
* LWORK (input) INTEGER
* The dimension of the array WORK.
* LWORK >= max( 1, MN + max( MN, NRHS ) ).
* For optimal performance,
* LWORK >= max( 1, MN + max( MN, NRHS )*NB ).
* where MN = min(M,N) and NB is the optimum block size.
*
* If LWORK = -1, then a workspace query is assumed; the routine
* only calculates the optimal size of the WORK array, returns
* this value as the first entry of the WORK array, and no error
* message related to LWORK is issued by XERBLA.
*
* INFO (output) INTEGER
* = 0: successful exit
* < 0: if INFO = -i, the i-th argument had an illegal value
*
* =====================================================================
*
* .. Parameters ..
|
Constructor Summary |
SGELS()
|
|
Method Summary |
static void |
SGELS(java.lang.String trans,
int m,
int n,
int nrhs,
float[][] a,
float[][] b,
float[] work,
int lwork,
intW info)
|
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
SGELS
public SGELS()
SGELS
public static void SGELS(java.lang.String trans,
int m,
int n,
int nrhs,
float[][] a,
float[][] b,
float[] work,
int lwork,
intW info)