Class DGEQP3

  extended by org.netlib.lapack.DGEQP3

public class DGEQP3
extends java.lang.Object

DGEQP3 is a simplified interface to the JLAPACK routine dgeqp3.
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 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
Method Summary
static void DGEQP3(int m, int n, double[][] a, int[] jpvt, double[] tau, double[] work, int lwork, intW info)
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public DGEQP3()
Method Detail


public static void DGEQP3(int m,
                          int n,
                          double[][] a,
                          int[] jpvt,
                          double[] tau,
                          double[] work,
                          int lwork,
                          intW info)