org.netlib.lapack
Class DLAGTF
java.lang.Object
org.netlib.lapack.DLAGTF
public class DLAGTF
 extends java.lang.Object
DLAGTF is a simplified interface to the JLAPACK routine dlagtf.
This interface converts Javastyle 2D rowmajor arrays into
the 1D columnmajor 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
* =======
*
* DLAGTF factorizes the matrix (T  lambda*I), where T is an n by n
* tridiagonal matrix and lambda is a scalar, as
*
* T  lambda*I = PLU,
*
* where P is a permutation matrix, L is a unit lower tridiagonal matrix
* with at most one nonzero subdiagonal elements per column and U is
* an upper triangular matrix with at most two nonzero superdiagonal
* elements per column.
*
* The factorization is obtained by Gaussian elimination with partial
* pivoting and implicit row scaling.
*
* The parameter LAMBDA is included in the routine so that DLAGTF may
* be used, in conjunction with DLAGTS, to obtain eigenvectors of T by
* inverse iteration.
*
* Arguments
* =========
*
* N (input) INTEGER
* The order of the matrix T.
*
* A (input/output) DOUBLE PRECISION array, dimension (N)
* On entry, A must contain the diagonal elements of T.
*
* On exit, A is overwritten by the n diagonal elements of the
* upper triangular matrix U of the factorization of T.
*
* LAMBDA (input) DOUBLE PRECISION
* On entry, the scalar lambda.
*
* B (input/output) DOUBLE PRECISION array, dimension (N1)
* On entry, B must contain the (n1) superdiagonal elements of
* T.
*
* On exit, B is overwritten by the (n1) superdiagonal
* elements of the matrix U of the factorization of T.
*
* C (input/output) DOUBLE PRECISION array, dimension (N1)
* On entry, C must contain the (n1) subdiagonal elements of
* T.
*
* On exit, C is overwritten by the (n1) subdiagonal elements
* of the matrix L of the factorization of T.
*
* TOL (input) DOUBLE PRECISION
* On entry, a relative tolerance used to indicate whether or
* not the matrix (T  lambda*I) is nearly singular. TOL should
* normally be chose as approximately the largest relative error
* in the elements of T. For example, if the elements of T are
* correct to about 4 significant figures, then TOL should be
* set to about 5*10**(4). If TOL is supplied as less than eps,
* where eps is the relative machine precision, then the value
* eps is used in place of TOL.
*
* D (output) DOUBLE PRECISION array, dimension (N2)
* On exit, D is overwritten by the (n2) second superdiagonal
* elements of the matrix U of the factorization of T.
*
* IN (output) INTEGER array, dimension (N)
* On exit, IN contains details of the permutation matrix P. If
* an interchange occurred at the kth step of the elimination,
* then IN(k) = 1, otherwise IN(k) = 0. The element IN(n)
* returns the smallest positive integer j such that
*
* abs( u(j,j) ).le. norm( (T  lambda*I)(j) )*TOL,
*
* where norm( A(j) ) denotes the sum of the absolute values of
* the jth row of the matrix A. If no such j exists then IN(n)
* is returned as zero. If IN(n) is returned as positive, then a
* diagonal element of U is small, indicating that
* (T  lambda*I) is singular or nearly singular,
*
* INFO (output) INTEGER
* = 0 : successful exit
* .lt. 0: if INFO = k, the kth argument had an illegal value
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
DLAGTF(int n,
double[] a,
double lambda,
double[] b,
double[] c,
double tol,
double[] d,
int[] in,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
DLAGTF
public DLAGTF()
DLAGTF
public static void DLAGTF(int n,
double[] a,
double lambda,
double[] b,
double[] c,
double tol,
double[] d,
int[] in,
intW info)