org.netlib.lapack
Class SGGBAL
java.lang.Object
org.netlib.lapack.SGGBAL
public class SGGBAL
- extends java.lang.Object
SGGBAL is a simplified interface to the JLAPACK routine sggbal.
This interface converts Java-style 2D row-major arrays into
the 1D column-major linearized arrays expected by the lower
level JLAPACK routines. Using this interface also allows you
to omit offset and leading dimension arguments. However, because
of these conversions, these routines will be slower than the low
level ones. Following is the description from the original Fortran
source. Contact seymour@cs.utk.edu with any questions.
* ..
*
* Purpose
* =======
*
* SGGBAL balances a pair of general real matrices (A,B). This
* involves, first, permuting A and B by similarity transformations to
* isolate eigenvalues in the first 1 to ILO$-$1 and last IHI+1 to N
* elements on the diagonal; and second, applying a diagonal similarity
* transformation to rows and columns ILO to IHI to make the rows
* and columns as close in norm as possible. Both steps are optional.
*
* Balancing may reduce the 1-norm of the matrices, and improve the
* accuracy of the computed eigenvalues and/or eigenvectors in the
* generalized eigenvalue problem A*x = lambda*B*x.
*
* Arguments
* =========
*
* JOB (input) CHARACTER*1
* Specifies the operations to be performed on A and B:
* = 'N': none: simply set ILO = 1, IHI = N, LSCALE(I) = 1.0
* and RSCALE(I) = 1.0 for i = 1,...,N.
* = 'P': permute only;
* = 'S': scale only;
* = 'B': both permute and scale.
*
* N (input) INTEGER
* The order of the matrices A and B. N >= 0.
*
* A (input/output) REAL array, dimension (LDA,N)
* On entry, the input matrix A.
* On exit, A is overwritten by the balanced matrix.
* If JOB = 'N', A is not referenced.
*
* LDA (input) INTEGER
* The leading dimension of the array A. LDA >= max(1,N).
*
* B (input/output) REAL array, dimension (LDB,N)
* On entry, the input matrix B.
* On exit, B is overwritten by the balanced matrix.
* If JOB = 'N', B is not referenced.
*
* LDB (input) INTEGER
* The leading dimension of the array B. LDB >= max(1,N).
*
* ILO (output) INTEGER
* IHI (output) INTEGER
* ILO and IHI are set to integers such that on exit
* A(i,j) = 0 and B(i,j) = 0 if i > j and
* j = 1,...,ILO-1 or i = IHI+1,...,N.
* If JOB = 'N' or 'S', ILO = 1 and IHI = N.
*
* LSCALE (output) REAL array, dimension (N)
* Details of the permutations and scaling factors applied
* to the left side of A and B. If P(j) is the index of the
* row interchanged with row j, and D(j)
* is the scaling factor applied to row j, then
* LSCALE(j) = P(j) for J = 1,...,ILO-1
* = D(j) for J = ILO,...,IHI
* = P(j) for J = IHI+1,...,N.
* The order in which the interchanges are made is N to IHI+1,
* then 1 to ILO-1.
*
* RSCALE (output) REAL array, dimension (N)
* Details of the permutations and scaling factors applied
* to the right side of A and B. If P(j) is the index of the
* column interchanged with column j, and D(j)
* is the scaling factor applied to column j, then
* LSCALE(j) = P(j) for J = 1,...,ILO-1
* = D(j) for J = ILO,...,IHI
* = P(j) for J = IHI+1,...,N.
* The order in which the interchanges are made is N to IHI+1,
* then 1 to ILO-1.
*
* WORK (workspace) REAL array, dimension (6*N)
*
* INFO (output) INTEGER
* = 0: successful exit
* < 0: if INFO = -i, the i-th argument had an illegal value.
*
* Further Details
* ===============
*
* See R.C. WARD, Balancing the generalized eigenvalue problem,
* SIAM J. Sci. Stat. Comp. 2 (1981), 141-152.
*
* =====================================================================
*
* .. Parameters ..
|
Method Summary |
static void |
SGGBAL(java.lang.String job,
int n,
float[][] a,
float[][] b,
intW ilo,
intW ihi,
float[] lscale,
float[] rscale,
float[] work,
intW info)
|
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
SGGBAL
public SGGBAL()
SGGBAL
public static void SGGBAL(java.lang.String job,
int n,
float[][] a,
float[][] b,
intW ilo,
intW ihi,
float[] lscale,
float[] rscale,
float[] work,
intW info)