org.netlib.lapack
Class DLAGTS
java.lang.Object
org.netlib.lapack.DLAGTS
public class DLAGTS
 extends java.lang.Object
DLAGTS is a simplified interface to the JLAPACK routine dlagts.
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
* =======
*
* DLAGTS may be used to solve one of the systems of equations
*
* (T  lambda*I)*x = y or (T  lambda*I)'*x = y,
*
* where T is an n by n tridiagonal matrix, for x, following the
* factorization of (T  lambda*I) as
*
* (T  lambda*I) = P*L*U ,
*
* by routine DLAGTF. The choice of equation to be solved is
* controlled by the argument JOB, and in each case there is an option
* to perturb zero or very small diagonal elements of U, this option
* being intended for use in applications such as inverse iteration.
*
* Arguments
* =========
*
* JOB (input) INTEGER
* Specifies the job to be performed by DLAGTS as follows:
* = 1: The equations (T  lambda*I)x = y are to be solved,
* but diagonal elements of U are not to be perturbed.
* = 1: The equations (T  lambda*I)x = y are to be solved
* and, if overflow would otherwise occur, the diagonal
* elements of U are to be perturbed. See argument TOL
* below.
* = 2: The equations (T  lambda*I)'x = y are to be solved,
* but diagonal elements of U are not to be perturbed.
* = 2: The equations (T  lambda*I)'x = y are to be solved
* and, if overflow would otherwise occur, the diagonal
* elements of U are to be perturbed. See argument TOL
* below.
*
* N (input) INTEGER
* The order of the matrix T.
*
* A (input) DOUBLE PRECISION array, dimension (N)
* On entry, A must contain the diagonal elements of U as
* returned from DLAGTF.
*
* B (input) DOUBLE PRECISION array, dimension (N1)
* On entry, B must contain the first superdiagonal elements of
* U as returned from DLAGTF.
*
* C (input) DOUBLE PRECISION array, dimension (N1)
* On entry, C must contain the subdiagonal elements of L as
* returned from DLAGTF.
*
* D (input) DOUBLE PRECISION array, dimension (N2)
* On entry, D must contain the second superdiagonal elements
* of U as returned from DLAGTF.
*
* IN (input) INTEGER array, dimension (N)
* On entry, IN must contain details of the matrix P as returned
* from DLAGTF.
*
* Y (input/output) DOUBLE PRECISION array, dimension (N)
* On entry, the right hand side vector y.
* On exit, Y is overwritten by the solution vector x.
*
* TOL (input/output) DOUBLE PRECISION
* On entry, with JOB .lt. 0, TOL should be the minimum
* perturbation to be made to very small diagonal elements of U.
* TOL should normally be chosen as about eps*norm(U), where eps
* is the relative machine precision, but if TOL is supplied as
* nonpositive, then it is reset to eps*max( abs( u(i,j) ) ).
* If JOB .gt. 0 then TOL is not referenced.
*
* On exit, TOL is changed as described above, only if TOL is
* nonpositive on entry. Otherwise TOL is unchanged.
*
* INFO (output) INTEGER
* = 0 : successful exit
* .lt. 0: if INFO = i, the ith argument had an illegal value
* .gt. 0: overflow would occur when computing the INFO(th)
* element of the solution vector x. This can only occur
* when JOB is supplied as positive and either means
* that a diagonal element of U is very small, or that
* the elements of the righthand side vector y are very
* large.
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
DLAGTS(int job,
int n,
double[] a,
double[] b,
double[] c,
double[] d,
int[] in,
double[] y,
doubleW tol,
intW info)

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