org.netlib.lapack
Class DGELS
java.lang.Object
org.netlib.lapack.DGELS
public class DGELS
 extends java.lang.Object
DGELS is a simplified interface to the JLAPACK routine dgels.
This interface converts Javastyle 2D rowmajor arrays into
the 1D columnmajor 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
* =======
*
* DGELS solves overdetermined or underdetermined real linear systems
* involving an MbyN 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
* MbyNRHS right hand side matrix B and the NbyNRHS 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) DOUBLE PRECISION array, dimension (LDA,N)
* On entry, the MbyN matrix A.
* On exit,
* if M >= N, A is overwritten by details of its QR
* factorization as returned by DGEQRF;
* if M < N, A is overwritten by details of its LQ
* factorization as returned by DGELQF.
*
* LDA (input) INTEGER
* The leading dimension of the array A. LDA >= max(1,M).
*
* B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
* On entry, the matrix B of right hand side vectors, stored
* columnwise; B is MbyNRHS if TRANS = 'N', or NbyNRHS
* 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) DOUBLE PRECISION 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 ith argument had an illegal value
*
* =====================================================================
*
* .. Parameters ..
Constructor Summary 
DGELS()

Method Summary 
static void 
DGELS(java.lang.String trans,
int m,
int n,
int nrhs,
double[][] a,
double[][] b,
double[] work,
int lwork,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
DGELS
public DGELS()
DGELS
public static void DGELS(java.lang.String trans,
int m,
int n,
int nrhs,
double[][] a,
double[][] b,
double[] work,
int lwork,
intW info)