org.netlib.lapack
Class Dgeqp3

java.lang.Object
  org.netlib.lapack.Dgeqp3

public class Dgeqp3
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
 *  =======
 *
 *  DGEQP3 computes a QR factorization with column pivoting of a
 *  matrix A:  A*P = Q*R  using Level 3 BLAS.
 *
 *  Arguments
 *  =========
 *
 *  M       (input) INTEGER
 *          The number of rows of the matrix A. M >= 0.
 *
 *  N       (input) INTEGER
 *          The number of columns of the matrix A.  N >= 0.
 *
 *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
 *          On entry, the M-by-N matrix A.
 *          On exit, the upper triangle of the array contains the
 *          min(M,N)-by-N upper trapezoidal matrix R; the elements below

 *          the diagonal, together with the array TAU, represent the
 *          orthogonal matrix Q as a product of min(M,N) elementary
 *          reflectors.
 *
 *  LDA     (input) INTEGER
 *          The leading dimension of the array A. LDA >= max(1,M).
 *
 *  JPVT    (input/output) INTEGER array, dimension (N)
 *          On entry, if JPVT(J).ne.0, the J-th column of A is permuted
 *          to the front of A*P (a leading column); if JPVT(J)=0,
 *          the J-th column of A is a free column.
 *          On exit, if JPVT(J)=K, then the J-th column of A*P was the
 *          the K-th column of A.
 *
 *  TAU     (output) DOUBLE PRECISION array, dimension (min(M,N))
 *          The scalar factors of the elementary reflectors.
 *
 *  WORK    (workspace/output) DOUBLE PRECISION array, dimension (LWORK)

 *          On exit, if INFO=0, WORK(1) returns the optimal LWORK.
 *
 *  LWORK   (input) INTEGER
 *          The dimension of the array WORK. LWORK >= 3*N+1.
 *          For optimal performance LWORK >= 2*N+( N+1 )*NB, where NB
 *          is the optimal blocksize.
 *
 *          If LWORK = -1, then a workspace query is assumed; the routine
 *          only calculates the optimal size of the WORK array, returns
 *          this value as the first entry of the WORK array, and no error
 *          message related to LWORK is issued by XERBLA.
 *
 *  INFO    (output) INTEGER
 *          = 0: successful exit.
 *          < 0: if INFO = -i, the i-th argument had an illegal value.
 *
 *  Further Details
 *  ===============
 *
 *  The matrix Q is represented as a product of elementary reflectors
 *
 *     Q = H(1) H(2) . . . H(k), where k = min(m,n).
 *
 *  Each H(i) has the form
 *
 *     H(i) = I - tau * v * v'
 *
 *  where tau is a real/complex scalar, and v is a real/complex vector
 *  with v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in
 *  A(i+1:m,i), and tau in TAU(i).
 *
 *  Based on contributions by
 *    G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain
 *    X. Sun, Computer Science Dept., Duke University, USA
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

Dgeqp3()

Method Summary

static void

dgeqp3(int m, int n, double[] a, int _a_offset, int lda, int[] jpvt, int _jpvt_offset, double[] tau, int _tau_offset, double[] work, int _work_offset, int lwork, intW info)

Methods inherited from class java.lang.Object

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

Constructor Detail

Dgeqp3

public Dgeqp3()

Method Detail

dgeqp3

public static void dgeqp3(int m,
                          int n,
                          double[] a,
                          int _a_offset,
                          int lda,
                          int[] jpvt,
                          int _jpvt_offset,
                          double[] tau,
                          int _tau_offset,
                          double[] work,
                          int _work_offset,
                          int lwork,
                          intW info)