org.netlib.lapack
Class Slahqr
java.lang.Object
org.netlib.lapack.Slahqr
public class Slahqr
- 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
* =======
*
* SLAHQR is an auxiliary routine called by SHSEQR to update the
* eigenvalues and Schur decomposition already computed by SHSEQR, by
* dealing with the Hessenberg submatrix in rows and columns ILO to IHI.
*
* Arguments
* =========
*
* WANTT (input) LOGICAL
* = .TRUE. : the full Schur form T is required;
* = .FALSE.: only eigenvalues are required.
*
* WANTZ (input) LOGICAL
* = .TRUE. : the matrix of Schur vectors Z is required;
* = .FALSE.: Schur vectors are not required.
*
* N (input) INTEGER
* The order of the matrix H. N >= 0.
*
* ILO (input) INTEGER
* IHI (input) INTEGER
* It is assumed that H is already upper quasi-triangular in
* rows and columns IHI+1:N, and that H(ILO,ILO-1) = 0 (unless
* ILO = 1). SLAHQR works primarily with the Hessenberg
* submatrix in rows and columns ILO to IHI, but applies
* transformations to all of H if WANTT is .TRUE..
* 1 <= ILO <= max(1,IHI); IHI <= N.
*
* H (input/output) REAL array, dimension (LDH,N)
* On entry, the upper Hessenberg matrix H.
* On exit, if WANTT is .TRUE., H is upper quasi-triangular in
* rows and columns ILO:IHI, with any 2-by-2 diagonal blocks in
* standard form. If WANTT is .FALSE., the contents of H are
* unspecified on exit.
*
* LDH (input) INTEGER
* The leading dimension of the array H. LDH >= max(1,N).
*
* WR (output) REAL array, dimension (N)
* WI (output) REAL array, dimension (N)
* The real and imaginary parts, respectively, of the computed
* eigenvalues ILO to IHI are stored in the corresponding
* elements of WR and WI. If two eigenvalues are computed as a
* complex conjugate pair, they are stored in consecutive
* elements of WR and WI, say the i-th and (i+1)th, with
* WI(i) > 0 and WI(i+1) < 0. If WANTT is .TRUE., the
* eigenvalues are stored in the same order as on the diagonal
* of the Schur form returned in H, with WR(i) = H(i,i), and, if
* H(i:i+1,i:i+1) is a 2-by-2 diagonal block,
* WI(i) = sqrt(H(i+1,i)*H(i,i+1)) and WI(i+1) = -WI(i).
*
* ILOZ (input) INTEGER
* IHIZ (input) INTEGER
* Specify the rows of Z to which transformations must be
* applied if WANTZ is .TRUE..
* 1 <= ILOZ <= ILO; IHI <= IHIZ <= N.
*
* Z (input/output) REAL array, dimension (LDZ,N)
* If WANTZ is .TRUE., on entry Z must contain the current
* matrix Z of transformations accumulated by SHSEQR, and on
* exit Z has been updated; transformations are applied only to
* the submatrix Z(ILOZ:IHIZ,ILO:IHI).
* If WANTZ is .FALSE., Z is not referenced.
*
* LDZ (input) INTEGER
* The leading dimension of the array Z. LDZ >= max(1,N).
*
* INFO (output) INTEGER
* = 0: successful exit
* > 0: SLAHQR failed to compute all the eigenvalues ILO to IHI
* in a total of 30*(IHI-ILO+1) iterations; if INFO = i,
* elements i+1:ihi of WR and WI contain those eigenvalues
* which have been successfully computed.
*
* Further Details
* ===============
*
* 2-96 Based on modifications by
* David Day, Sandia National Laboratory, USA
*
* =====================================================================
*
* .. Parameters ..
|
Method Summary |
static void |
slahqr(boolean wantt,
boolean wantz,
int n,
int ilo,
int ihi,
float[] h,
int _h_offset,
int ldh,
float[] wr,
int _wr_offset,
float[] wi,
int _wi_offset,
int iloz,
int ihiz,
float[] z,
int _z_offset,
int ldz,
intW info)
|
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Slahqr
public Slahqr()
slahqr
public static void slahqr(boolean wantt,
boolean wantz,
int n,
int ilo,
int ihi,
float[] h,
int _h_offset,
int ldh,
float[] wr,
int _wr_offset,
float[] wi,
int _wi_offset,
int iloz,
int ihiz,
float[] z,
int _z_offset,
int ldz,
intW info)