org.netlib.lapack
Class DLALSD
java.lang.Object
org.netlib.lapack.DLALSD
public class DLALSD
 extends java.lang.Object
DLALSD is a simplified interface to the JLAPACK routine dlalsd.
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
* =======
*
* DLALSD uses the singular value decomposition of A to solve the least
* squares problem of finding X to minimize the Euclidean norm of each
* column of A*XB, where A is NbyN upper bidiagonal, and X and B
* are NbyNRHS. The solution X overwrites B.
*
* The singular values of A smaller than RCOND times the largest
* singular value are treated as zero in solving the least squares
* problem; in this case a minimum norm solution is returned.
* The actual singular values are returned in D in ascending order.
*
* This code makes very mild assumptions about floating point
* arithmetic. It will work on machines with a guard digit in
* add/subtract, or on those binary machines without guard digits
* which subtract like the Cray XMP, Cray YMP, Cray C 90, or Cray 2.
* It could conceivably fail on hexadecimal or decimal machines
* without guard digits, but we know of none.
*
* Arguments
* =========
*
* UPLO (input) CHARACTER*1
* = 'U': D and E define an upper bidiagonal matrix.
* = 'L': D and E define a lower bidiagonal matrix.
*
* SMLSIZ (input) INTEGER
* The maximum size of the subproblems at the bottom of the
* computation tree.
*
* N (input) INTEGER
* The dimension of the bidiagonal matrix. N >= 0.
*
* NRHS (input) INTEGER
* The number of columns of B. NRHS must be at least 1.
*
* D (input/output) DOUBLE PRECISION array, dimension (N)
* On entry D contains the main diagonal of the bidiagonal
* matrix. On exit, if INFO = 0, D contains its singular values.
*
* E (input) DOUBLE PRECISION array, dimension (N1)
* Contains the superdiagonal entries of the bidiagonal matrix.
* On exit, E has been destroyed.
*
* B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
* On input, B contains the right hand sides of the least
* squares problem. On output, B contains the solution X.
*
* LDB (input) INTEGER
* The leading dimension of B in the calling subprogram.
* LDB must be at least max(1,N).
*
* RCOND (input) DOUBLE PRECISION
* The singular values of A less than or equal to RCOND times
* the largest singular value are treated as zero in solving
* the least squares problem. If RCOND is negative,
* machine precision is used instead.
* For example, if diag(S)*X=B were the least squares problem,
* where diag(S) is a diagonal matrix of singular values, the
* solution would be X(i) = B(i) / S(i) if S(i) is greater than
* RCOND*max(S), and X(i) = 0 if S(i) is less than or equal to
* RCOND*max(S).
*
* RANK (output) INTEGER
* The number of singular values of A greater than RCOND times
* the largest singular value.
*
* WORK (workspace) DOUBLE PRECISION array, dimension at least
* (9*N + 2*N*SMLSIZ + 8*N*NLVL + N*NRHS + (SMLSIZ+1)**2),
* where NLVL = max(0, INT(log_2 (N/(SMLSIZ+1))) + 1).
*
* IWORK (workspace) INTEGER array, dimension at least
* (3*N*NLVL + 11*N)
*
* INFO (output) INTEGER
* = 0: successful exit.
* < 0: if INFO = i, the ith argument had an illegal value.
* > 0: The algorithm failed to compute an singular value while
* working on the submatrix lying in rows and columns
* INFO/(N+1) through MOD(INFO,N+1).
*
* Further Details
* ===============
*
* Based on contributions by
* Ming Gu and RenCang Li, Computer Science Division, University of
* California at Berkeley, USA
* Osni Marques, LBNL/NERSC, USA
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
DLALSD(java.lang.String uplo,
int smlsiz,
int n,
int nrhs,
double[] d,
double[] e,
double[][] b,
doubleW rcond,
intW rank,
double[] work,
int[] iwork,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
DLALSD
public DLALSD()
DLALSD
public static void DLALSD(java.lang.String uplo,
int smlsiz,
int n,
int nrhs,
double[] d,
double[] e,
double[][] b,
doubleW rcond,
intW rank,
double[] work,
int[] iwork,
intW info)