org.netlib.lapack
Class Dtrexc
java.lang.Object
org.netlib.lapack.Dtrexc
public class Dtrexc
 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
* =======
*
* DTREXC reorders the real Schur factorization of a real matrix
* A = Q*T*Q**T, so that the diagonal block of T with row index IFST is
* moved to row ILST.
*
* The real Schur form T is reordered by an orthogonal similarity
* transformation Z**T*T*Z, and optionally the matrix Q of Schur vectors
* is updated by postmultiplying it with Z.
*
* T must be in Schur canonical form (as returned by DHSEQR), that is,
* block upper triangular with 1by1 and 2by2 diagonal blocks; each
* 2by2 diagonal block has its diagonal elements equal and its
* offdiagonal elements of opposite sign.
*
* Arguments
* =========
*
* COMPQ (input) CHARACTER*1
* = 'V': update the matrix Q of Schur vectors;
* = 'N': do not update Q.
*
* N (input) INTEGER
* The order of the matrix T. N >= 0.
*
* T (input/output) DOUBLE PRECISION array, dimension (LDT,N)
* On entry, the upper quasitriangular matrix T, in Schur
* Schur canonical form.
* On exit, the reordered upper quasitriangular matrix, again
* in Schur canonical form.
*
* LDT (input) INTEGER
* The leading dimension of the array T. LDT >= max(1,N).
*
* Q (input/output) DOUBLE PRECISION array, dimension (LDQ,N)
* On entry, if COMPQ = 'V', the matrix Q of Schur vectors.
* On exit, if COMPQ = 'V', Q has been postmultiplied by the
* orthogonal transformation matrix Z which reorders T.
* If COMPQ = 'N', Q is not referenced.
*
* LDQ (input) INTEGER
* The leading dimension of the array Q. LDQ >= max(1,N).
*
* IFST (input/output) INTEGER
* ILST (input/output) INTEGER
* Specify the reordering of the diagonal blocks of T.
* The block with row index IFST is moved to row ILST, by a
* sequence of transpositions between adjacent blocks.
* On exit, if IFST pointed on entry to the second row of a
* 2by2 block, it is changed to point to the first row; ILST
* always points to the first row of the block in its final
* position (which may differ from its input value by +1 or 1).
* 1 <= IFST <= N; 1 <= ILST <= N.
*
* WORK (workspace) DOUBLE PRECISION array, dimension (N)
*
* INFO (output) INTEGER
* = 0: successful exit
* < 0: if INFO = i, the ith argument had an illegal value
* = 1: two adjacent blocks were too close to swap (the problem
* is very illconditioned); T may have been partially
* reordered, and ILST points to the first row of the
* current position of the block being moved.
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
dtrexc(java.lang.String compq,
int n,
double[] t,
int _t_offset,
int ldt,
double[] q,
int _q_offset,
int ldq,
intW ifst,
intW ilst,
double[] work,
int _work_offset,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Dtrexc
public Dtrexc()
dtrexc
public static void dtrexc(java.lang.String compq,
int n,
double[] t,
int _t_offset,
int ldt,
double[] q,
int _q_offset,
int ldq,
intW ifst,
intW ilst,
double[] work,
int _work_offset,
intW info)