org.netlib.arpack
Class Dseupd

java.lang.Object
  extended by org.netlib.arpack.Dseupd

public class Dseupd
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.

*\BeginDoc \Name: dseupd \Description: This subroutine returns the converged approximations to eigenvalues of A*z = lambda*B*z and (optionally): (1) the corresponding approximate eigenvectors, (2) an orthonormal (Lanczos) basis for the associated approximate invariant subspace, (3) Both. There is negligible additional cost to obtain eigenvectors. An orthonormal (Lanczos) basis is always computed. There is an additional storage cost of n*nev if both are requested (in this case a separate array Z must be supplied). These quantities are obtained from the Lanczos factorization computed by DSAUPD for the linear operator OP prescribed by the MODE selection (see IPARAM(7) in DSAUPD documentation.) DSAUPD must be called before this routine is called. These approximate eigenvalues and vectors are commonly called Ritz values and Ritz vectors respectively. They are referred to as such in the comments that follow. The computed orthonormal basis for the invariant subspace corresponding to these Ritz values is referred to as a Lanczos basis. See documentation in the header of the subroutine DSAUPD for a definition of OP as well as other terms and the relation of computed Ritz values and vectors of OP with respect to the given problem A*z = lambda*B*z. The approximate eigenvalues of the original problem are returned in ascending algebraic order. The user may elect to call this routine once for each desired Ritz vector and store it peripherally if desired. There is also the option of computing a selected set of these vectors with a single call. \Usage: call dseupd ( RVEC, HOWMNY, SELECT, D, Z, LDZ, SIGMA, BMAT, N, WHICH, NEV, TOL, RESID, NCV, V, LDV, IPARAM, IPNTR, WORKD, WORKL, LWORKL, INFO ) RVEC LOGICAL (INPUT) Specifies whether Ritz vectors corresponding to the Ritz value approximations to the eigenproblem A*z = lambda*B*z are computed. RVEC = .FALSE. Compute Ritz values only. RVEC = .TRUE. Compute Ritz vectors. HOWMNY Character*1 (INPUT) Specifies how many Ritz vectors are wanted and the form of Z the matrix of Ritz vectors. See remark 1 below. = 'A': compute NEV Ritz vectors; = 'S': compute some of the Ritz vectors, specified by the logical array SELECT. SELECT Logical array of dimension NCV. (INPUT/WORKSPACE) If HOWMNY = 'S', SELECT specifies the Ritz vectors to be computed. To select the Ritz vector corresponding to a Ritz value D(j), SELECT(j) must be set to .TRUE.. If HOWMNY = 'A' , SELECT is used as a workspace for reordering the Ritz values. D Double precision array of dimension NEV. (OUTPUT) On exit, D contains the Ritz value approximations to the eigenvalues of A*z = lambda*B*z. The values are returned in ascending order. If IPARAM(7) = 3,4,5 then D represents the Ritz values of OP computed by dsaupd transformed to those of the original eigensystem A*z = lambda*B*z. If IPARAM(7) = 1,2 then the Ritz values of OP are the same as the those of A*z = lambda*B*z. Z Double precision N by NEV array if HOWMNY = 'A'. (OUTPUT) On exit, Z contains the B-orthonormal Ritz vectors of the eigensystem A*z = lambda*B*z corresponding to the Ritz value approximations. If RVEC = .FALSE. then Z is not referenced. NOTE: The array Z may be set equal to first NEV columns of the Arnoldi/Lanczos basis array V computed by DSAUPD . LDZ Integer. (INPUT) The leading dimension of the array Z. If Ritz vectors are desired, then LDZ .ge. max( 1, N ). In any case, LDZ .ge. 1. SIGMA Double precision (INPUT) If IPARAM(7) = 3,4,5 represents the shift. Not referenced if IPARAM(7) = 1 or 2. **** The remaining arguments MUST be the same as for the **** **** call to DSAUPD that was just completed. **** NOTE: The remaining arguments BMAT, N, WHICH, NEV, TOL, RESID, NCV, V, LDV, IPARAM, IPNTR, WORKD, WORKL, LWORKL, INFO must be passed directly to DSEUPD following the last call to DSAUPD . These arguments MUST NOT BE MODIFIED between the the last call to DSAUPD and the call to DSEUPD . Two of these parameters (WORKL, INFO) are also output parameters: WORKL Double precision work array of length LWORKL. (OUTPUT/WORKSPACE) WORKL(1:4*ncv) contains information obtained in dsaupd . They are not changed by dseupd . WORKL(4*ncv+1:ncv*ncv+8*ncv) holds the untransformed Ritz values, the computed error estimates, and the associated eigenvector matrix of H. Note: IPNTR(8:10) contains the pointer into WORKL for addresses of the above information computed by dseupd . ------------------------------------------------------------- IPNTR(8): pointer to the NCV RITZ values of the original system. IPNTR(9): pointer to the NCV corresponding error bounds. IPNTR(10): pointer to the NCV by NCV matrix of eigenvectors of the tridiagonal matrix T. Only referenced by dseupd if RVEC = .TRUE. See Remarks. ------------------------------------------------------------- INFO Integer. (OUTPUT) Error flag on output. = 0: Normal exit. = -1: N must be positive. = -2: NEV must be positive. = -3: NCV must be greater than NEV and less than or equal to N. = -5: WHICH must be one of 'LM', 'SM', 'LA', 'SA' or 'BE'. = -6: BMAT must be one of 'I' or 'G'. = -7: Length of private work WORKL array is not sufficient. = -8: Error return from trid. eigenvalue calculation; Information error from LAPACK routine dsteqr . = -9: Starting vector is zero. = -10: IPARAM(7) must be 1,2,3,4,5. = -11: IPARAM(7) = 1 and BMAT = 'G' are incompatible. = -12: NEV and WHICH = 'BE' are incompatible. = -14: DSAUPD did not find any eigenvalues to sufficient accuracy. = -15: HOWMNY must be one of 'A' or 'S' if RVEC = .true. = -16: HOWMNY = 'S' not yet implemented = -17: DSEUPD got a different count of the number of converged Ritz values than DSAUPD got. This indicates the user probably made an error in passing data from DSAUPD to DSEUPD or that the data was modified before entering DSEUPD . \BeginLib \References: 1. D.C. Sorensen, "Implicit Application of Polynomial Filters in a k-Step Arnoldi Method", SIAM J. Matr. Anal. Apps., 13 (1992), pp 357-385. 2. R.B. Lehoucq, "Analysis and Implementation of an Implicitly Restarted Arnoldi Iteration", Rice University Technical Report TR95-13, Department of Computational and Applied Mathematics. 3. B.N. Parlett, "The Symmetric Eigenvalue Problem". Prentice-Hall, 1980. 4. B.N. Parlett, B. Nour-Omid, "Towards a Black Box Lanczos Program", Computer Physics Communications, 53 (1989), pp 169-179. 5. B. Nour-Omid, B.N. Parlett, T. Ericson, P.S. Jensen, "How to Implement the Spectral Transformation", Math. Comp., 48 (1987), pp 663-673. 6. R.G. Grimes, J.G. Lewis and H.D. Simon, "A Shifted Block Lanczos Algorithm for Solving Sparse Symmetric Generalized Eigenproblems", SIAM J. Matr. Anal. Apps., January (1993). 7. L. Reichel, W.B. Gragg, "Algorithm 686: FORTRAN Subroutines for Updating the QR decomposition", ACM TOMS, December 1990, Volume 16 Number 4, pp 369-377. \Remarks 1. The converged Ritz values are always returned in increasing (algebraic) order. 2. Currently only HOWMNY = 'A' is implemented. It is included at this stage for the user who wants to incorporate it. \Routines called: dsesrt ARPACK routine that sorts an array X, and applies the corresponding permutation to a matrix A. dsortr dsortr ARPACK sorting routine. ivout ARPACK utility routine that prints integers. dvout ARPACK utility routine that prints vectors. dgeqr2 LAPACK routine that computes the QR factorization of a matrix. dlacpy LAPACK matrix copy routine. dlamch LAPACK routine that determines machine constants. dorm2r LAPACK routine that applies an orthogonal matrix in factored form. dsteqr LAPACK routine that computes eigenvalues and eigenvectors of a tridiagonal matrix. dger Level 2 BLAS rank one update to a matrix. dcopy Level 1 BLAS that copies one vector to another . dnrm2 Level 1 BLAS that computes the norm of a vector. dscal Level 1 BLAS that scales a vector. dswap Level 1 BLAS that swaps the contents of two vectors. \Authors Danny Sorensen Phuong Vu Richard Lehoucq CRPC / Rice University Chao Yang Houston, Texas Dept. of Computational & Applied Mathematics Rice University Houston, Texas \Revision history: 12/15/93: Version ' 2.1' \SCCS Information: @(#) FILE: seupd.F SID: 2.11 DATE OF SID: 04/10/01 RELEASE: 2 \EndLib -----------------------------------------------------------------------


Field Summary
static float t0
           
static float t1
           
static float t2
           
static float t3
           
static float t4
           
static float t5
           
 
Constructor Summary
Dseupd()
           
 
Method Summary
static void dseupd(boolean rvec, java.lang.String howmny, boolean[] select, int _select_offset, double[] d, int _d_offset, double[] z, int _z_offset, int ldz, double sigma, java.lang.String bmat, int n, java.lang.String which, org.netlib.util.intW nev, double tol, double[] resid, int _resid_offset, int ncv, double[] v, int _v_offset, int ldv, int[] iparam, int _iparam_offset, int[] ipntr, int _ipntr_offset, double[] workd, int _workd_offset, double[] workl, int _workl_offset, int lworkl, org.netlib.util.intW info)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

t0

public static float t0

t1

public static float t1

t2

public static float t2

t3

public static float t3

t4

public static float t4

t5

public static float t5
Constructor Detail

Dseupd

public Dseupd()
Method Detail

dseupd

public static void dseupd(boolean rvec,
                          java.lang.String howmny,
                          boolean[] select,
                          int _select_offset,
                          double[] d,
                          int _d_offset,
                          double[] z,
                          int _z_offset,
                          int ldz,
                          double sigma,
                          java.lang.String bmat,
                          int n,
                          java.lang.String which,
                          org.netlib.util.intW nev,
                          double tol,
                          double[] resid,
                          int _resid_offset,
                          int ncv,
                          double[] v,
                          int _v_offset,
                          int ldv,
                          int[] iparam,
                          int _iparam_offset,
                          int[] ipntr,
                          int _ipntr_offset,
                          double[] workd,
                          int _workd_offset,
                          double[] workl,
                          int _workl_offset,
                          int lworkl,
                          org.netlib.util.intW info)