Class DGERQ2

  extended by org.netlib.lapack.DGERQ2

public class DGERQ2
extends java.lang.Object

DGERQ2 is a simplified interface to the JLAPACK routine dgerq2.
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 * ======= * * DGERQ2 computes an RQ factorization of a real m by n matrix A: * A = R * Q. * * 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, if m <= n, the upper triangle of the subarray * A(1:m,n-m+1:n) contains the m by m upper triangular matrix R; * if m >= n, the elements on and above the (m-n)-th subdiagonal * contain the m by n upper trapezoidal matrix R; the remaining * elements, with the array TAU, represent the orthogonal matrix * Q as a product of elementary reflectors (see Further * Details). * * LDA (input) INTEGER * The leading dimension of the array A. LDA >= max(1,M). * * TAU (output) DOUBLE PRECISION array, dimension (min(M,N)) * The scalar factors of the elementary reflectors (see Further * Details). * * WORK (workspace) DOUBLE PRECISION array, dimension (M) * * 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 scalar, and v is a real vector with * v(n-k+i+1:n) = 0 and v(n-k+i) = 1; v(1:n-k+i-1) is stored on exit in * A(m-k+i,1:n-k+i-1), and tau in TAU(i). * * ===================================================================== * * .. Parameters ..

Constructor Summary
Method Summary
static void DGERQ2(int m, int n, double[][] a, double[] tau, double[] work, intW info)
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public DGERQ2()
Method Detail


public static void DGERQ2(int m,
                          int n,
                          double[][] a,
                          double[] tau,
                          double[] work,
                          intW info)