org.netlib.lapack
Class Dlatdf

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

public class Dlatdf
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 * ======= * * DLATDF uses the LU factorization of the n-by-n matrix Z computed by * DGETC2 and computes a contribution to the reciprocal Dif-estimate * by solving Z * x = b for x, and choosing the r.h.s. b such that * the norm of x is as large as possible. On entry RHS = b holds the * contribution from earlier solved sub-systems, and on return RHS = x. * * The factorization of Z returned by DGETC2 has the form Z = P*L*U*Q, * where P and Q are permutation matrices. L is lower triangular with * unit diagonal elements and U is upper triangular. * * Arguments * ========= * * IJOB (input) INTEGER * IJOB = 2: First compute an approximative null-vector e * of Z using DGECON, e is normalized and solve for * Zx = +-e - f with the sign giving the greater value * of 2-norm(x). About 5 times as expensive as Default. * IJOB .ne. 2: Local look ahead strategy where all entries of * the r.h.s. b is choosen as either +1 or -1 (Default). * * N (input) INTEGER * The number of columns of the matrix Z. * * Z (input) DOUBLE PRECISION array, dimension (LDZ, N) * On entry, the LU part of the factorization of the n-by-n * matrix Z computed by DGETC2: Z = P * L * U * Q * * LDZ (input) INTEGER * The leading dimension of the array Z. LDA >= max(1, N). * * RHS (input/output) DOUBLE PRECISION array, dimension N. * On entry, RHS contains contributions from other subsystems. * On exit, RHS contains the solution of the subsystem with * entries acoording to the value of IJOB (see above). * * RDSUM (input/output) DOUBLE PRECISION * On entry, the sum of squares of computed contributions to * the Dif-estimate under computation by DTGSYL, where the * scaling factor RDSCAL (see below) has been factored out. * On exit, the corresponding sum of squares updated with the * contributions from the current sub-system. * If TRANS = 'T' RDSUM is not touched. * NOTE: RDSUM only makes sense when DTGSY2 is called by STGSYL. * * RDSCAL (input/output) DOUBLE PRECISION * On entry, scaling factor used to prevent overflow in RDSUM. * On exit, RDSCAL is updated w.r.t. the current contributions * in RDSUM. * If TRANS = 'T', RDSCAL is not touched. * NOTE: RDSCAL only makes sense when DTGSY2 is called by * DTGSYL. * * IPIV (input) INTEGER array, dimension (N). * The pivot indices; for 1 <= i <= N, row i of the * matrix has been interchanged with row IPIV(i). * * JPIV (input) INTEGER array, dimension (N). * The pivot indices; for 1 <= j <= N, column j of the * matrix has been interchanged with column JPIV(j). * * Further Details * =============== * * Based on contributions by * Bo Kagstrom and Peter Poromaa, Department of Computing Science, * Umea University, S-901 87 Umea, Sweden. * * This routine is a further developed implementation of algorithm * BSOLVE in [1] using complete pivoting in the LU factorization. * * [1] Bo Kagstrom and Lars Westin, * Generalized Schur Methods with Condition Estimators for * Solving the Generalized Sylvester Equation, IEEE Transactions * on Automatic Control, Vol. 34, No. 7, July 1989, pp 745-751. * * [2] Peter Poromaa, * On Efficient and Robust Estimators for the Separation * between two Regular Matrix Pairs with Applications in * Condition Estimation. Report IMINF-95.05, Departement of * Computing Science, Umea University, S-901 87 Umea, Sweden, 1995. * * ===================================================================== * * .. Parameters ..


Constructor Summary
Dlatdf()
           
 
Method Summary
static void dlatdf(int ijob, int n, double[] z, int _z_offset, int ldz, double[] rhs, int _rhs_offset, doubleW rdsum, doubleW rdscal, int[] ipiv, int _ipiv_offset, int[] jpiv, int _jpiv_offset)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Dlatdf

public Dlatdf()
Method Detail

dlatdf

public static void dlatdf(int ijob,
                          int n,
                          double[] z,
                          int _z_offset,
                          int ldz,
                          double[] rhs,
                          int _rhs_offset,
                          doubleW rdsum,
                          doubleW rdscal,
                          int[] ipiv,
                          int _ipiv_offset,
                          int[] jpiv,
                          int _jpiv_offset)