org.netlib.lapack
Class Dlarzt

java.lang.Object
  extended by org.netlib.lapack.Dlarzt

public class Dlarzt
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 * ======= * * 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, int _v_offset, int ldv, double[] tau, int _tau_offset, double[] t, int _t_offset, int ldt)
           
 
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,
                          int _v_offset,
                          int ldv,
                          double[] tau,
                          int _tau_offset,
                          double[] t,
                          int _t_offset,
                          int ldt)