org.netlib.lapack
Class DLARZT

java.lang.Object
  org.netlib.lapack.DLARZT

public class DLARZT
extends java.lang.Object

DLARZT is a simplified interface to the JLAPACK routine dlarzt.
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
 *  =======
 *
 *  DLARZT forms the triangular factor T of a real block reflector
 *  H of order > n, which is defined as a product of k elementary
 *  reflectors.
 *
 *  If DIRECT = 'F', H = H(1) H(2) . . . H(k) and T is upper triangular;

 *
 *  If DIRECT = 'B', H = H(k) . . . H(2) H(1) and T is lower triangular.

 *
 *  If STOREV = 'C', the vector which defines the elementary reflector
 *  H(i) is stored in the i-th column of the array V, and
 *
 *     H  =  I - V * T * V'
 *
 *  If STOREV = 'R', the vector which defines the elementary reflector
 *  H(i) is stored in the i-th row of the array V, and
 *
 *     H  =  I - V' * T * V
 *
 *  Currently, only STOREV = 'R' and DIRECT = 'B' are supported.
 *
 *  Arguments
 *  =========
 *
 *  DIRECT  (input) CHARACTER*1
 *          Specifies the order in which the elementary reflectors are
 *          multiplied to form the block reflector:
 *          = 'F': H = H(1) H(2) . . . H(k) (Forward, not supported yet)

 *          = 'B': H = H(k) . . . H(2) H(1) (Backward)
 *
 *  STOREV  (input) CHARACTER*1
 *          Specifies how the vectors which define the elementary
 *          reflectors are stored (see also Further Details):
 *          = 'C': columnwise                        (not supported yet)

 *          = 'R': rowwise
 *
 *  N       (input) INTEGER
 *          The order of the block reflector H. N >= 0.
 *
 *  K       (input) INTEGER
 *          The order of the triangular factor T (= the number of
 *          elementary reflectors). K >= 1.
 *
 *  V       (input/output) DOUBLE PRECISION array, dimension
 *                               (LDV,K) if STOREV = 'C'
 *                               (LDV,N) if STOREV = 'R'
 *          The matrix V. See further details.
 *
 *  LDV     (input) INTEGER
 *          The leading dimension of the array V.
 *          If STOREV = 'C', LDV >= max(1,N); if STOREV = 'R', LDV >= K.

 *
 *  TAU     (input) DOUBLE PRECISION array, dimension (K)
 *          TAU(i) must contain the scalar factor of the elementary
 *          reflector H(i).
 *
 *  T       (output) DOUBLE PRECISION array, dimension (LDT,K)
 *          The k by k triangular factor T of the block reflector.
 *          If DIRECT = 'F', T is upper triangular; if DIRECT = 'B', T is
 *          lower triangular. The rest of the array is not used.
 *
 *  LDT     (input) INTEGER
 *          The leading dimension of the array T. LDT >= K.
 *
 *  Further Details
 *  ===============
 *
 *  Based on contributions by
 *    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

 *
 *  The shape of the matrix V and the storage of the vectors which define
 *  the H(i) is best illustrated by the following example with n = 5 and

 *  k = 3. The elements equal to 1 are not stored; the corresponding
 *  array elements are modified but restored on exit. The rest of the
 *  array is not used.
 *
 *  DIRECT = 'F' and STOREV = 'C':         DIRECT = 'F' and STOREV = 'R':
 *
 *                                              ______V_____
 *         ( v1 v2 v3 )                        /            \
 *         ( v1 v2 v3 )                      ( v1 v1 v1 v1 v1 . . . . 1 )
 *     V = ( v1 v2 v3 )                      ( v2 v2 v2 v2 v2 . . . 1   )
 *         ( v1 v2 v3 )                      ( v3 v3 v3 v3 v3 . . 1     )
 *         ( v1 v2 v3 )
 *            .  .  .
 *            .  .  .
 *            1  .  .
 *               1  .
 *                  1
 *
 *  DIRECT = 'B' and STOREV = 'C':         DIRECT = 'B' and STOREV = 'R':
 *
 *                                                        ______V_____
 *            1                                          /            \
 *            .  1                           ( 1 . . . . v1 v1 v1 v1 v1 )
 *            .  .  1                        ( . 1 . . . v2 v2 v2 v2 v2 )
 *            .  .  .                        ( . . 1 . . v3 v3 v3 v3 v3 )
 *            .  .  .
 *         ( v1 v2 v3 )
 *         ( v1 v2 v3 )
 *     V = ( v1 v2 v3 )
 *         ( v1 v2 v3 )
 *         ( v1 v2 v3 )
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

DLARZT()

Method Summary

static void

DLARZT(java.lang.String direct, java.lang.String storev, int n, int k, double[][] v, double[] tau, double[][] t)

Methods inherited from class java.lang.Object

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

Constructor Detail

DLARZT

public DLARZT()

Method Detail

DLARZT

public static void DLARZT(java.lang.String direct,
                          java.lang.String storev,
                          int n,
                          int k,
                          double[][] v,
                          double[] tau,
                          double[][] t)