org.netlib.lapack
Class SLAED2
java.lang.Object
org.netlib.lapack.SLAED2
public class SLAED2
 extends java.lang.Object
SLAED2 is a simplified interface to the JLAPACK routine slaed2.
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
* =======
*
* SLAED2 merges the two sets of eigenvalues together into a single
* sorted set. Then it tries to deflate the size of the problem.
* There are two ways in which deflation can occur: when two or more
* eigenvalues are close together or if there is a tiny entry in the
* Z vector. For each such occurrence the order of the related secular
* equation problem is reduced by one.
*
* Arguments
* =========
*
* K (output) INTEGER
* The number of nondeflated eigenvalues, and the order of the
* related secular equation. 0 <= K <=N.
*
* N (input) INTEGER
* The dimension of the symmetric tridiagonal matrix. N >= 0.
*
* N1 (input) INTEGER
* The location of the last eigenvalue in the leading submatrix.
* min(1,N) <= N1 <= N/2.
*
* D (input/output) REAL array, dimension (N)
* On entry, D contains the eigenvalues of the two submatrices to
* be combined.
* On exit, D contains the trailing (NK) updated eigenvalues
* (those which were deflated) sorted into increasing order.
*
* Q (input/output) REAL array, dimension (LDQ, N)
* On entry, Q contains the eigenvectors of two submatrices in
* the two square blocks with corners at (1,1), (N1,N1)
* and (N1+1, N1+1), (N,N).
* On exit, Q contains the trailing (NK) updated eigenvectors
* (those which were deflated) in its last NK columns.
*
* LDQ (input) INTEGER
* The leading dimension of the array Q. LDQ >= max(1,N).
*
* INDXQ (input/output) INTEGER array, dimension (N)
* The permutation which separately sorts the two subproblems
* in D into ascending order. Note that elements in the second
* half of this permutation must first have N1 added to their
* values. Destroyed on exit.
*
* RHO (input/output) REAL
* On entry, the offdiagonal element associated with the rank1
* cut which originally split the two submatrices which are now
* being recombined.
* On exit, RHO has been modified to the value required by
* SLAED3.
*
* Z (input) REAL array, dimension (N)
* On entry, Z contains the updating vector (the last
* row of the first subeigenvector matrix and the first row of
* the second subeigenvector matrix).
* On exit, the contents of Z have been destroyed by the updating
* process.
*
* DLAMDA (output) REAL array, dimension (N)
* A copy of the first K eigenvalues which will be used by
* SLAED3 to form the secular equation.
*
* W (output) REAL array, dimension (N)
* The first k values of the final deflationaltered zvector
* which will be passed to SLAED3.
*
* Q2 (output) REAL array, dimension (N1**2+(NN1)**2)
* A copy of the first K eigenvectors which will be used by
* SLAED3 in a matrix multiply (SGEMM) to solve for the new
* eigenvectors.
*
* INDX (workspace) INTEGER array, dimension (N)
* The permutation used to sort the contents of DLAMDA into
* ascending order.
*
* INDXC (output) INTEGER array, dimension (N)
* The permutation used to arrange the columns of the deflated
* Q matrix into three groups: the first group contains nonzero
* elements only at and above N1, the second contains
* nonzero elements only below N1, and the third is dense.
*
* INDXP (workspace) INTEGER array, dimension (N)
* The permutation used to place deflated values of D at the end
* of the array. INDXP(1:K) points to the nondeflated Dvalues
* and INDXP(K+1:N) points to the deflated eigenvalues.
*
* COLTYP (workspace/output) INTEGER array, dimension (N)
* During execution, a label which will indicate which of the
* following types a column in the Q2 matrix is:
* 1 : nonzero in the upper half only;
* 2 : dense;
* 3 : nonzero in the lower half only;
* 4 : deflated.
* On exit, COLTYP(i) is the number of columns of type i,
* for i=1 to 4 only.
*
* INFO (output) INTEGER
* = 0: successful exit.
* < 0: if INFO = i, the ith argument had an illegal value.
*
* Further Details
* ===============
*
* Based on contributions by
* Jeff Rutter, Computer Science Division, University of California
* at Berkeley, USA
* Modified by Francoise Tisseur, University of Tennessee.
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
SLAED2(intW k,
int n,
int n1,
float[] d,
float[][] q,
int[] indxq,
floatW rho,
float[] z,
float[] dlamda,
float[] w,
float[] q2,
int[] indx,
int[] indxc,
int[] indxp,
int[] coltyp,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
SLAED2
public SLAED2()
SLAED2
public static void SLAED2(intW k,
int n,
int n1,
float[] d,
float[][] q,
int[] indxq,
floatW rho,
float[] z,
float[] dlamda,
float[] w,
float[] q2,
int[] indx,
int[] indxc,
int[] indxp,
int[] coltyp,
intW info)