org.netlib.lapack
Class Dlagv2

java.lang.Object
  org.netlib.lapack.Dlagv2

public class Dlagv2
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
 *  =======
 *
 *  DLAGV2 computes the Generalized Schur factorization of a real 2-by-2

 *  matrix pencil (A,B) where B is upper triangular. This routine
 *  computes orthogonal (rotation) matrices given by CSL, SNL and CSR,
 *  SNR such that
 *
 *  1) if the pencil (A,B) has two real eigenvalues (include 0/0 or 1/0
 *     types), then
 *
 *     [ a11 a12 ] := [  CSL  SNL ] [ a11 a12 ] [  CSR -SNR ]
 *     [  0  a22 ]    [ -SNL  CSL ] [ a21 a22 ] [  SNR  CSR ]
 *
 *     [ b11 b12 ] := [  CSL  SNL ] [ b11 b12 ] [  CSR -SNR ]
 *     [  0  b22 ]    [ -SNL  CSL ] [  0  b22 ] [  SNR  CSR ],
 *
 *  2) if the pencil (A,B) has a pair of complex conjugate eigenvalues,
 *     then
 *
 *     [ a11 a12 ] := [  CSL  SNL ] [ a11 a12 ] [  CSR -SNR ]
 *     [ a21 a22 ]    [ -SNL  CSL ] [ a21 a22 ] [  SNR  CSR ]
 *
 *     [ b11  0  ] := [  CSL  SNL ] [ b11 b12 ] [  CSR -SNR ]
 *     [  0  b22 ]    [ -SNL  CSL ] [  0  b22 ] [  SNR  CSR ]
 *
 *     where b11 >= b22 > 0.
 *
 *
 *  Arguments
 *  =========
 *
 *  A       (input/output) DOUBLE PRECISION array, dimension (LDA, 2)
 *          On entry, the 2 x 2 matrix A.
 *          On exit, A is overwritten by the ``A-part'' of the
 *          generalized Schur form.
 *
 *  LDA     (input) INTEGER
 *          THe leading dimension of the array A.  LDA >= 2.
 *
 *  B       (input/output) DOUBLE PRECISION array, dimension (LDB, 2)
 *          On entry, the upper triangular 2 x 2 matrix B.
 *          On exit, B is overwritten by the ``B-part'' of the
 *          generalized Schur form.
 *
 *  LDB     (input) INTEGER
 *          THe leading dimension of the array B.  LDB >= 2.
 *
 *  ALPHAR  (output) DOUBLE PRECISION array, dimension (2)
 *  ALPHAI  (output) DOUBLE PRECISION array, dimension (2)
 *  BETA    (output) DOUBLE PRECISION array, dimension (2)
 *          (ALPHAR(k)+i*ALPHAI(k))/BETA(k) are the eigenvalues of the
 *          pencil (A,B), k=1,2, i = sqrt(-1).  Note that BETA(k) may
 *          be zero.
 *
 *  CSL     (output) DOUBLE PRECISION
 *          The cosine of the left rotation matrix.
 *
 *  SNL     (output) DOUBLE PRECISION
 *          The sine of the left rotation matrix.
 *
 *  CSR     (output) DOUBLE PRECISION
 *          The cosine of the right rotation matrix.
 *
 *  SNR     (output) DOUBLE PRECISION
 *          The sine of the right rotation matrix.
 *
 *  Further Details
 *  ===============
 *
 *  Based on contributions by
 *     Mark Fahey, Department of Mathematics, Univ. of Kentucky, USA
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

Dlagv2()

Method Summary

static void

dlagv2(double[] a, int _a_offset, int lda, double[] b, int _b_offset, int ldb, double[] alphar, int _alphar_offset, double[] alphai, int _alphai_offset, double[] beta, int _beta_offset, doubleW csl, doubleW snl, doubleW csr, doubleW snr)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Dlagv2

public Dlagv2()

Method Detail

dlagv2

public static void dlagv2(double[] a,
                          int _a_offset,
                          int lda,
                          double[] b,
                          int _b_offset,
                          int ldb,
                          double[] alphar,
                          int _alphar_offset,
                          double[] alphai,
                          int _alphai_offset,
                          double[] beta,
                          int _beta_offset,
                          doubleW csl,
                          doubleW snl,
                          doubleW csr,
                          doubleW snr)