org.netlib.arpack
Class Dstqrb

java.lang.Object
  extended by org.netlib.arpack.Dstqrb

public class Dstqrb
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.

*----------------------------------------------------------------------- \BeginDoc \Name: dstqrb \Description: Computes all eigenvalues and the last component of the eigenvectors of a symmetric tridiagonal matrix using the implicit QL or QR method. This is mostly a modification of the LAPACK routine dsteqr. See Remarks. \Usage: call dstqrb ( N, D, E, Z, WORK, INFO ) \Arguments N Integer. (INPUT) The number of rows and columns in the matrix. N >= 0. D Double precision array, dimension (N). (INPUT/OUTPUT) On entry, D contains the diagonal elements of the tridiagonal matrix. On exit, D contains the eigenvalues, in ascending order. If an error exit is made, the eigenvalues are correct for indices 1,2,...,INFO-1, but they are unordered and may not be the smallest eigenvalues of the matrix. E Double precision array, dimension (N-1). (INPUT/OUTPUT) On entry, E contains the subdiagonal elements of the tridiagonal matrix in positions 1 through N-1. On exit, E has been destroyed. Z Double precision array, dimension (N). (OUTPUT) On exit, Z contains the last row of the orthonormal eigenvector matrix of the symmetric tridiagonal matrix. If an error exit is made, Z contains the last row of the eigenvector matrix associated with the stored eigenvalues. WORK Double precision array, dimension (max(1,2*N-2)). (WORKSPACE) Workspace used in accumulating the transformation for computing the last components of the eigenvectors. INFO Integer. (OUTPUT) = 0: normal return. < 0: if INFO = -i, the i-th argument had an illegal value. > 0: if INFO = +i, the i-th eigenvalue has not converged after a total of 30*N iterations. \Remarks 1. None. ----------------------------------------------------------------------- \BeginLib \Local variables: xxxxxx real \Routines called: daxpy Level 1 BLAS that computes a vector triad. dcopy Level 1 BLAS that copies one vector to another. dswap Level 1 BLAS that swaps the contents of two vectors. lsame LAPACK character comparison routine. dlae2 LAPACK routine that computes the eigenvalues of a 2-by-2 symmetric matrix. dlaev2 LAPACK routine that eigendecomposition of a 2-by-2 symmetric matrix. dlamch LAPACK routine that determines machine constants. dlanst LAPACK routine that computes the norm of a matrix. dlapy2 LAPACK routine to compute sqrt(x**2+y**2) carefully. dlartg LAPACK Givens rotation construction routine. dlascl LAPACK routine for careful scaling of a matrix. dlaset LAPACK matrix initialization routine. dlasr LAPACK routine that applies an orthogonal transformation to a matrix. dlasrt LAPACK sorting routine. dsteqr LAPACK routine that computes eigenvalues and eigenvectors of a symmetric tridiagonal matrix. xerbla LAPACK error handler routine. \Authors Danny Sorensen Phuong Vu Richard Lehoucq CRPC / Rice University Dept. of Computational & Houston, Texas Applied Mathematics Rice University Houston, Texas \SCCS Information: @(#) FILE: stqrb.F SID: 2.5 DATE OF SID: 8/27/96 RELEASE: 2 \Remarks 1. Starting with version 2.5, this routine is a modified version of LAPACK version 2.0 subroutine SSTEQR. No lines are deleted, only commeted out and new lines inserted. All lines commented out have "c$$$" at the beginning. Note that the LAPACK version 1.0 subroutine SSTEQR contained bugs. \EndLib -----------------------------------------------------------------------


Constructor Summary
Dstqrb()
           
 
Method Summary
static void dstqrb(int n, double[] d, int _d_offset, double[] e, int _e_offset, double[] z, int _z_offset, double[] work, int _work_offset, org.netlib.util.intW info)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Dstqrb

public Dstqrb()
Method Detail

dstqrb

public static void dstqrb(int n,
                          double[] d,
                          int _d_offset,
                          double[] e,
                          int _e_offset,
                          double[] z,
                          int _z_offset,
                          double[] work,
                          int _work_offset,
                          org.netlib.util.intW info)