org.netlib.lapack
Class DLACN2
java.lang.Object
org.netlib.lapack.DLACN2
public class DLACN2
- extends java.lang.Object
DLACN2 is a simplified interface to the JLAPACK routine dlacn2.
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
* =======
*
* DLACN2 estimates the 1-norm of a square, real matrix A.
* Reverse communication is used for evaluating matrix-vector products.
*
* Arguments
* =========
*
* N (input) INTEGER
* The order of the matrix. N >= 1.
*
* V (workspace) DOUBLE PRECISION array, dimension (N)
* On the final return, V = A*W, where EST = norm(V)/norm(W)
* (W is not returned).
*
* X (input/output) DOUBLE PRECISION array, dimension (N)
* On an intermediate return, X should be overwritten by
* A * X, if KASE=1,
* A' * X, if KASE=2,
* and DLACN2 must be re-called with all the other parameters
* unchanged.
*
* ISGN (workspace) INTEGER array, dimension (N)
*
* EST (input/output) DOUBLE PRECISION
* On entry with KASE = 1 or 2 and ISAVE(1) = 3, EST should be
* unchanged from the previous call to DLACN2.
* On exit, EST is an estimate (a lower bound) for norm(A).
*
* KASE (input/output) INTEGER
* On the initial call to DLACN2, KASE should be 0.
* On an intermediate return, KASE will be 1 or 2, indicating
* whether X should be overwritten by A * X or A' * X.
* On the final return from DLACN2, KASE will again be 0.
*
* ISAVE (input/output) INTEGER array, dimension (3)
* ISAVE is used to save variables between calls to DLACN2
*
* Further Details
* ======= =======
*
* Contributed by Nick Higham, University of Manchester.
* Originally named SONEST, dated March 16, 1988.
*
* Reference: N.J. Higham, "FORTRAN codes for estimating the one-norm of
* a real or complex matrix, with applications to condition estimation",
* ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988.
*
* This is a thread safe version of DLACON, which uses the array ISAVE
* in place of a SAVE statement, as follows:
*
* DLACON DLACN2
* JUMP ISAVE(1)
* J ISAVE(2)
* ITER ISAVE(3)
*
* =====================================================================
*
* .. Parameters ..
Method Summary |
static void |
DLACN2(int n,
double[] v,
double[] x,
int[] isgn,
doubleW est,
intW kase,
int[] isave)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
DLACN2
public DLACN2()
DLACN2
public static void DLACN2(int n,
double[] v,
double[] x,
int[] isgn,
doubleW est,
intW kase,
int[] isave)