org.netlib.lapack
Class Dlagts

java.lang.Object
  extended by org.netlib.lapack.Dlagts

public class Dlagts
extends java.lang.Object

Following is the description from the original
Fortran source.  For each array argument, the Java
version will include an integer offset parameter, so
the arguments may not match the description exactly.
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 (N-1) * On entry, B must contain the first super-diagonal elements of * U as returned from DLAGTF. * * C (input) DOUBLE PRECISION array, dimension (N-1) * On entry, C must contain the sub-diagonal elements of L as * returned from DLAGTF. * * D (input) DOUBLE PRECISION array, dimension (N-2) * On entry, D must contain the second super-diagonal 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 * non-positive, 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 * non-positive on entry. Otherwise TOL is unchanged. * * INFO (output) INTEGER * = 0 : successful exit * .lt. 0: if INFO = -i, the i-th 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 right-hand side vector y are very * large. * * ===================================================================== * * .. Parameters ..


Constructor Summary
Dlagts()
           
 
Method Summary
static void dlagts(int job, int n, double[] a, int _a_offset, double[] b, int _b_offset, double[] c, int _c_offset, double[] d, int _d_offset, int[] in, int _in_offset, double[] y, int _y_offset, doubleW tol, intW info)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Dlagts

public Dlagts()
Method Detail

dlagts

public static void dlagts(int job,
                          int n,
                          double[] a,
                          int _a_offset,
                          double[] b,
                          int _b_offset,
                          double[] c,
                          int _c_offset,
                          double[] d,
                          int _d_offset,
                          int[] in,
                          int _in_offset,
                          double[] y,
                          int _y_offset,
                          doubleW tol,
                          intW info)