org.netlib.lapack
Class Slatdf
java.lang.Object
org.netlib.lapack.Slatdf
public class Slatdf
- 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
* =======
*
* SLATDF uses the LU factorization of the n-by-n matrix Z computed by
* SGETC2 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 SGETC2 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 SGECON, 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) REAL array, dimension (LDZ, N)
* On entry, the LU part of the factorization of the n-by-n
* matrix Z computed by SGETC2: Z = P * L * U * Q
*
* LDZ (input) INTEGER
* The leading dimension of the array Z. LDA >= max(1, N).
*
* RHS (input/output) REAL 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) REAL
* On entry, the sum of squares of computed contributions to
* the Dif-estimate under computation by STGSYL, 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 STGSY2 is called by STGSYL.
*
* RDSCAL (input/output) REAL
* 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 STGSY2 is called by
* STGSYL.
*
* 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 ..
|
Method Summary |
static void |
slatdf(int ijob,
int n,
float[] z,
int _z_offset,
int ldz,
float[] rhs,
int _rhs_offset,
floatW rdsum,
floatW 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 |
Slatdf
public Slatdf()
slatdf
public static void slatdf(int ijob,
int n,
float[] z,
int _z_offset,
int ldz,
float[] rhs,
int _rhs_offset,
floatW rdsum,
floatW rdscal,
int[] ipiv,
int _ipiv_offset,
int[] jpiv,
int _jpiv_offset)