org.netlib.lapack
Class DLAGV2
java.lang.Object
org.netlib.lapack.DLAGV2
public class DLAGV2
- extends java.lang.Object
DLAGV2 is a simplified interface to the JLAPACK routine dlagv2.
This interface converts Java-style 2D row-major arrays into
the 1D column-major 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
* =======
*
* 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 ..
Method Summary |
static void |
DLAGV2(double[][] a,
double[][] b,
double[] alphar,
double[] alphai,
double[] beta,
org.netlib.util.doubleW csl,
org.netlib.util.doubleW snl,
org.netlib.util.doubleW csr,
org.netlib.util.doubleW snr)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
DLAGV2
public DLAGV2()
DLAGV2
public static void DLAGV2(double[][] a,
double[][] b,
double[] alphar,
double[] alphai,
double[] beta,
org.netlib.util.doubleW csl,
org.netlib.util.doubleW snl,
org.netlib.util.doubleW csr,
org.netlib.util.doubleW snr)