org.netlib.lapack
Class Dsygv

java.lang.Object
  org.netlib.lapack.Dsygv

public class Dsygv
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
 *  =======
 *
 *  DSYGV computes all the eigenvalues, and optionally, the eigenvectors

 *  of a real generalized symmetric-definite eigenproblem, of the form
 *  A*x=(lambda)*B*x,  A*Bx=(lambda)*x,  or B*A*x=(lambda)*x.
 *  Here A and B are assumed to be symmetric and B is also
 *  positive definite.
 *
 *  Arguments
 *  =========
 *
 *  ITYPE   (input) INTEGER
 *          Specifies the problem type to be solved:
 *          = 1:  A*x = (lambda)*B*x
 *          = 2:  A*B*x = (lambda)*x
 *          = 3:  B*A*x = (lambda)*x
 *
 *  JOBZ    (input) CHARACTER*1
 *          = 'N':  Compute eigenvalues only;
 *          = 'V':  Compute eigenvalues and eigenvectors.
 *
 *  UPLO    (input) CHARACTER*1
 *          = 'U':  Upper triangles of A and B are stored;
 *          = 'L':  Lower triangles of A and B are stored.
 *
 *  N       (input) INTEGER
 *          The order of the matrices A and B.  N >= 0.
 *
 *  A       (input/output) DOUBLE PRECISION array, dimension (LDA, N)
 *          On entry, the symmetric matrix A.  If UPLO = 'U', the
 *          leading N-by-N upper triangular part of A contains the
 *          upper triangular part of the matrix A.  If UPLO = 'L',
 *          the leading N-by-N lower triangular part of A contains
 *          the lower triangular part of the matrix A.
 *
 *          On exit, if JOBZ = 'V', then if INFO = 0, A contains the
 *          matrix Z of eigenvectors.  The eigenvectors are normalized
 *          as follows:
 *          if ITYPE = 1 or 2, Z**T*B*Z = I;
 *          if ITYPE = 3, Z**T*inv(B)*Z = I.
 *          If JOBZ = 'N', then on exit the upper triangle (if UPLO='U')

 *          or the lower triangle (if UPLO='L') of A, including the
 *          diagonal, is destroyed.
 *
 *  LDA     (input) INTEGER
 *          The leading dimension of the array A.  LDA >= max(1,N).
 *
 *  B       (input/output) DOUBLE PRECISION array, dimension (LDB, N)
 *          On entry, the symmetric positive definite matrix B.
 *          If UPLO = 'U', the leading N-by-N upper triangular part of B

 *          contains the upper triangular part of the matrix B.
 *          If UPLO = 'L', the leading N-by-N lower triangular part of B

 *          contains the lower triangular part of the matrix B.
 *
 *          On exit, if INFO <= N, the part of B containing the matrix is
 *          overwritten by the triangular factor U or L from the Cholesky
 *          factorization B = U**T*U or B = L*L**T.
 *
 *  LDB     (input) INTEGER
 *          The leading dimension of the array B.  LDB >= max(1,N).
 *
 *  W       (output) DOUBLE PRECISION array, dimension (N)
 *          If INFO = 0, the eigenvalues in ascending order.
 *
 *  WORK    (workspace/output) DOUBLE PRECISION array, dimension (LWORK)

 *          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
 *
 *  LWORK   (input) INTEGER
 *          The length of the array WORK.  LWORK >= max(1,3*N-1).
 *          For optimal efficiency, LWORK >= (NB+2)*N,
 *          where NB is the blocksize for DSYTRD returned by ILAENV.
 *
 *          If LWORK = -1, then a workspace query is assumed; the routine
 *          only calculates the optimal size of the WORK array, returns
 *          this value as the first entry of the WORK array, and no error
 *          message related to LWORK is issued by XERBLA.
 *
 *  INFO    (output) INTEGER
 *          = 0:  successful exit
 *          < 0:  if INFO = -i, the i-th argument had an illegal value
 *          > 0:  DPOTRF or DSYEV returned an error code:
 *             <= N:  if INFO = i, DSYEV failed to converge;
 *                    i off-diagonal elements of an intermediate
 *                    tridiagonal form did not converge to zero;
 *             > N:   if INFO = N + i, for 1 <= i <= N, then the leading

 *                    minor of order i of B is not positive definite.
 *                    The factorization of B could not be completed and
 *                    no eigenvalues or eigenvectors were computed.
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

Dsygv()

Method Summary

static void

dsygv(int itype, java.lang.String jobz, java.lang.String uplo, int n, double[] a, int _a_offset, int lda, double[] b, int _b_offset, int ldb, double[] w, int _w_offset, double[] work, int _work_offset, int lwork, intW info)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Dsygv

public Dsygv()

Method Detail

dsygv

public static void dsygv(int itype,
                         java.lang.String jobz,
                         java.lang.String uplo,
                         int n,
                         double[] a,
                         int _a_offset,
                         int lda,
                         double[] b,
                         int _b_offset,
                         int ldb,
                         double[] w,
                         int _w_offset,
                         double[] work,
                         int _work_offset,
                         int lwork,
                         intW info)