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 firstname.lastname@example.org with any questions.
* 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 1-by-1 and 2-by-2 diagonal blocks; each
* 2-by-2 diagonal block has its diagonal elements equal and its
* off-diagonal elements of opposite sign.
* 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 quasi-triangular matrix T, in Schur
* Schur canonical form.
* On exit, the reordered upper quasi-triangular 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
* 2-by-2 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 i-th argument had an illegal value
* = 1: two adjacent blocks were too close to swap (the problem
* is very ill-conditioned); T may have been partially
* reordered, and ILST points to the first row of the
* current position of the block being moved.
* .. Parameters ..
|Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public static void dtrexc(java.lang.String compq,