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Class org.netlib.lapack.DGEQPF

java.lang.Object
   |
   +----org.netlib.lapack.DGEQPF

public class DGEQPF

extends Object

DGEQPF is a simplified interface to the JLAPACK routine dgeqpf.
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
 *  =======
 *
 *  DGEQPF computes a QR factorization with column pivoting of a
 *  real M-by-N matrix A: A*P = Q*R.
 *
 *  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 triangular 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(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.
 *
 *  WORK    (workspace) DOUBLE PRECISION array, dimension (3*N)
 *
 *  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(n)
 *
 *  Each H(i) has the form
 *
 *     H = I - tau * v * v'
 *
 *  where tau is a real scalar, and v is a real 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).
 *
 *  The matrix P is represented in jpvt as follows: If
 *     jpvt(j) = i
 *  then the jth column of P is the ith canonical unit vector.
 *
 *  =====================================================================
 *
 *     .. Parameters ..

DGEQPF()

DGEQPF(int, int, double[][], int[], double[], double[], intW)

 public DGEQPF()

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

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