org.netlib.lapack
Class SLAEV2

java.lang.Object
  org.netlib.lapack.SLAEV2

public class SLAEV2
extends java.lang.Object

SLAEV2 is a simplified interface to the JLAPACK routine slaev2.
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
 *  =======
 *
 *  SLAEV2 computes the eigendecomposition of a 2-by-2 symmetric matrix
 *     [  A   B  ]
 *     [  B   C  ].
 *  On return, RT1 is the eigenvalue of larger absolute value, RT2 is the
 *  eigenvalue of smaller absolute value, and (CS1,SN1) is the unit right
 *  eigenvector for RT1, giving the decomposition
 *
 *     [ CS1  SN1 ] [  A   B  ] [ CS1 -SN1 ]  =  [ RT1  0  ]
 *     [-SN1  CS1 ] [  B   C  ] [ SN1  CS1 ]     [  0  RT2 ].
 *
 *  Arguments
 *  =========
 *
 *  A       (input) REAL
 *          The (1,1) element of the 2-by-2 matrix.
 *
 *  B       (input) REAL
 *          The (1,2) element and the conjugate of the (2,1) element of
 *          the 2-by-2 matrix.
 *
 *  C       (input) REAL
 *          The (2,2) element of the 2-by-2 matrix.
 *
 *  RT1     (output) REAL
 *          The eigenvalue of larger absolute value.
 *
 *  RT2     (output) REAL
 *          The eigenvalue of smaller absolute value.
 *
 *  CS1     (output) REAL
 *  SN1     (output) REAL
 *          The vector (CS1, SN1) is a unit right eigenvector for RT1.
 *
 *  Further Details
 *  ===============
 *
 *  RT1 is accurate to a few ulps barring over/underflow.
 *
 *  RT2 may be inaccurate if there is massive cancellation in the
 *  determinant A*C-B*B; higher precision or correctly rounded or
 *  correctly truncated arithmetic would be needed to compute RT2
 *  accurately in all cases.
 *
 *  CS1 and SN1 are accurate to a few ulps barring over/underflow.
 *
 *  Overflow is possible only if RT1 is within a factor of 5 of overflow.
 *  Underflow is harmless if the input data is 0 or exceeds
 *     underflow_threshold / macheps.
 *
 * =====================================================================

 *
 *     .. Parameters ..

Constructor Summary

SLAEV2()

Method Summary

static void

SLAEV2(float a, float b, float c, floatW rt1, floatW rt2, floatW cs1, floatW sn1)

Methods inherited from class java.lang.Object

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

Constructor Detail

SLAEV2

public SLAEV2()

Method Detail

SLAEV2

public static void SLAEV2(float a,
                          float b,
                          float c,
                          floatW rt1,
                          floatW rt2,
                          floatW cs1,
                          floatW sn1)