org.netlib.lapack
Class DLAQP2
java.lang.Object
org.netlib.lapack.DLAQP2
public class DLAQP2
- extends java.lang.Object
DLAQP2 is a simplified interface to the JLAPACK routine dlaqp2.
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
* =======
*
* DLAQP2 computes a QR factorization with column pivoting of
* the block A(OFFSET+1:M,1:N).
* The block A(1:OFFSET,1:N) is accordingly pivoted, but not factorized.
*
* 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.
*
* OFFSET (input) INTEGER
* The number of rows of the matrix A that must be pivoted
* but no factorized. OFFSET >= 0.
*
* A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
* On entry, the M-by-N matrix A.
* On exit, the upper triangle of block A(OFFSET+1:M,1:N) is
* the triangular factor obtained; the elements in block
* A(OFFSET+1:M,1:N) below the diagonal, together with the
* array TAU, represent the orthogonal matrix Q as a product of
* elementary reflectors. Block A(1:OFFSET,1:N) has been
* accordingly pivoted, but no factorized.
*
* 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(i) .ne. 0, the i-th column of A is permuted
* to the front of A*P (a leading column); if JPVT(i) = 0,
* the i-th column of A is a free column.
* On exit, if JPVT(i) = k, then the i-th column of A*P
* was the k-th column of A.
*
* TAU (output) DOUBLE PRECISION array, dimension (min(M,N))
* The scalar factors of the elementary reflectors.
*
* VN1 (input/output) DOUBLE PRECISION array, dimension (N)
* The vector with the partial column norms.
*
* VN2 (input/output) DOUBLE PRECISION array, dimension (N)
* The vector with the exact column norms.
*
* WORK (workspace) DOUBLE PRECISION array, dimension (N)
*
* Further Details
* ===============
*
* Based on contributions by
* G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain
* X. Sun, Computer Science Dept., Duke University, USA
*
* Partial column norm updating strategy modified by
* Z. Drmac and Z. Bujanovic, Dept. of Mathematics,
* University of Zagreb, Croatia.
* June 2006.
* For more details see LAPACK Working Note 176.
* =====================================================================
*
* .. Parameters ..
Method Summary |
static void |
DLAQP2(int m,
int n,
int offset,
double[][] a,
int[] jpvt,
double[] tau,
double[] vn1,
double[] vn2,
double[] work)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
DLAQP2
public DLAQP2()
DLAQP2
public static void DLAQP2(int m,
int n,
int offset,
double[][] a,
int[] jpvt,
double[] tau,
double[] vn1,
double[] vn2,
double[] work)