org.netlib.lapack
Class Slalsa
java.lang.Object
org.netlib.lapack.Slalsa
public class Slalsa
- extends java.lang.Object
Following is the description from the original
Fortran source. For each array argument, the Java
version will include an integer offset parameter, so
the arguments may not match the description exactly.
Contact seymour@cs.utk.edu with any questions.
* ..
*
* Purpose
* =======
*
* SLALSA is an itermediate step in solving the least squares problem
* by computing the SVD of the coefficient matrix in compact form (The
* singular vectors are computed as products of simple orthorgonal
* matrices.).
*
* If ICOMPQ = 0, SLALSA applies the inverse of the left singular vector
* matrix of an upper bidiagonal matrix to the right hand side; and if
* ICOMPQ = 1, SLALSA applies the right singular vector matrix to the
* right hand side. The singular vector matrices were generated in
* compact form by SLALSA.
*
* Arguments
* =========
*
*
* ICOMPQ (input) INTEGER
* Specifies whether the left or the right singular vector
* matrix is involved.
* = 0: Left singular vector matrix
* = 1: Right singular vector matrix
*
* SMLSIZ (input) INTEGER
* The maximum size of the subproblems at the bottom of the
* computation tree.
*
* N (input) INTEGER
* The row and column dimensions of the upper bidiagonal matrix.
*
* NRHS (input) INTEGER
* The number of columns of B and BX. NRHS must be at least 1.
*
* B (input) REAL array, dimension ( LDB, NRHS )
* On input, B contains the right hand sides of the least
* squares problem in rows 1 through M. On output, B contains
* the solution X in rows 1 through N.
*
* LDB (input) INTEGER
* The leading dimension of B in the calling subprogram.
* LDB must be at least max(1,MAX( M, N ) ).
*
* BX (output) REAL array, dimension ( LDBX, NRHS )
* On exit, the result of applying the left or right singular
* vector matrix to B.
*
* LDBX (input) INTEGER
* The leading dimension of BX.
*
* U (input) REAL array, dimension ( LDU, SMLSIZ ).
* On entry, U contains the left singular vector matrices of all
* subproblems at the bottom level.
*
* LDU (input) INTEGER, LDU = > N.
* The leading dimension of arrays U, VT, DIFL, DIFR,
* POLES, GIVNUM, and Z.
*
* VT (input) REAL array, dimension ( LDU, SMLSIZ+1 ).
* On entry, VT' contains the right singular vector matrices of
* all subproblems at the bottom level.
*
* K (input) INTEGER array, dimension ( N ).
*
* DIFL (input) REAL array, dimension ( LDU, NLVL ).
* where NLVL = INT(log_2 (N/(SMLSIZ+1))) + 1.
*
* DIFR (input) REAL array, dimension ( LDU, 2 * NLVL ).
* On entry, DIFL(*, I) and DIFR(*, 2 * I -1) record
* distances between singular values on the I-th level and
* singular values on the (I -1)-th level, and DIFR(*, 2 * I)
* record the normalizing factors of the right singular vectors
* matrices of subproblems on I-th level.
*
* Z (input) REAL array, dimension ( LDU, NLVL ).
* On entry, Z(1, I) contains the components of the deflation-
* adjusted updating row vector for subproblems on the I-th
* level.
*
* POLES (input) REAL array, dimension ( LDU, 2 * NLVL ).
* On entry, POLES(*, 2 * I -1: 2 * I) contains the new and old
* singular values involved in the secular equations on the I-th
* level.
*
* GIVPTR (input) INTEGER array, dimension ( N ).
* On entry, GIVPTR( I ) records the number of Givens
* rotations performed on the I-th problem on the computation
* tree.
*
* GIVCOL (input) INTEGER array, dimension ( LDGCOL, 2 * NLVL ).
* On entry, for each I, GIVCOL(*, 2 * I - 1: 2 * I) records the
* locations of Givens rotations performed on the I-th level on
* the computation tree.
*
* LDGCOL (input) INTEGER, LDGCOL = > N.
* The leading dimension of arrays GIVCOL and PERM.
*
* PERM (input) INTEGER array, dimension ( LDGCOL, NLVL ).
* On entry, PERM(*, I) records permutations done on the I-th
* level of the computation tree.
*
* GIVNUM (input) REAL array, dimension ( LDU, 2 * NLVL ).
* On entry, GIVNUM(*, 2 *I -1 : 2 * I) records the C- and S-
* values of Givens rotations performed on the I-th level on the
* computation tree.
*
* C (input) REAL array, dimension ( N ).
* On entry, if the I-th subproblem is not square,
* C( I ) contains the C-value of a Givens rotation related to
* the right null space of the I-th subproblem.
*
* S (input) REAL array, dimension ( N ).
* On entry, if the I-th subproblem is not square,
* S( I ) contains the S-value of a Givens rotation related to
* the right null space of the I-th subproblem.
*
* WORK (workspace) REAL array.
* The dimension must be at least N.
*
* IWORK (workspace) INTEGER array.
* The dimension must be at least 3 * N
*
* INFO (output) INTEGER
* = 0: successful exit.
* < 0: if INFO = -i, the i-th argument had an illegal value.
*
* Further Details
* ===============
*
* Based on contributions by
* Ming Gu and Ren-Cang Li, Computer Science Division, University of
* California at Berkeley, USA
* Osni Marques, LBNL/NERSC, USA
*
* =====================================================================
*
* .. Parameters ..
|
Method Summary |
static void |
slalsa(int icompq,
int smlsiz,
int n,
int nrhs,
float[] b,
int _b_offset,
int ldb,
float[] bx,
int _bx_offset,
int ldbx,
float[] u,
int _u_offset,
int ldu,
float[] vt,
int _vt_offset,
int[] k,
int _k_offset,
float[] difl,
int _difl_offset,
float[] difr,
int _difr_offset,
float[] z,
int _z_offset,
float[] poles,
int _poles_offset,
int[] givptr,
int _givptr_offset,
int[] givcol,
int _givcol_offset,
int ldgcol,
int[] perm,
int _perm_offset,
float[] givnum,
int _givnum_offset,
float[] c,
int _c_offset,
float[] s,
int _s_offset,
float[] work,
int _work_offset,
int[] iwork,
int _iwork_offset,
intW info)
|
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Slalsa
public Slalsa()
slalsa
public static void slalsa(int icompq,
int smlsiz,
int n,
int nrhs,
float[] b,
int _b_offset,
int ldb,
float[] bx,
int _bx_offset,
int ldbx,
float[] u,
int _u_offset,
int ldu,
float[] vt,
int _vt_offset,
int[] k,
int _k_offset,
float[] difl,
int _difl_offset,
float[] difr,
int _difr_offset,
float[] z,
int _z_offset,
float[] poles,
int _poles_offset,
int[] givptr,
int _givptr_offset,
int[] givcol,
int _givcol_offset,
int ldgcol,
int[] perm,
int _perm_offset,
float[] givnum,
int _givnum_offset,
float[] c,
int _c_offset,
float[] s,
int _s_offset,
float[] work,
int _work_offset,
int[] iwork,
int _iwork_offset,
intW info)