org.netlib.lapack
Class Dpoequ

java.lang.Object
  org.netlib.lapack.Dpoequ

public class Dpoequ
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
 *  =======
 *
 *  DPOEQU computes row and column scalings intended to equilibrate a
 *  symmetric positive definite matrix A and reduce its condition number

 *  (with respect to the two-norm).  S contains the scale factors,
 *  S(i) = 1/sqrt(A(i,i)), chosen so that the scaled matrix B with
 *  elements B(i,j) = S(i)*A(i,j)*S(j) has ones on the diagonal.  This
 *  choice of S puts the condition number of B within a factor N of the
 *  smallest possible condition number over all possible diagonal
 *  scalings.
 *
 *  Arguments
 *  =========
 *
 *  N       (input) INTEGER
 *          The order of the matrix A.  N >= 0.
 *
 *  A       (input) DOUBLE PRECISION array, dimension (LDA,N)
 *          The N-by-N symmetric positive definite matrix whose scaling
 *          factors are to be computed.  Only the diagonal elements of A

 *          are referenced.
 *
 *  LDA     (input) INTEGER
 *          The leading dimension of the array A.  LDA >= max(1,N).
 *
 *  S       (output) DOUBLE PRECISION array, dimension (N)
 *          If INFO = 0, S contains the scale factors for A.
 *
 *  SCOND   (output) DOUBLE PRECISION
 *          If INFO = 0, S contains the ratio of the smallest S(i) to
 *          the largest S(i).  If SCOND >= 0.1 and AMAX is neither too
 *          large nor too small, it is not worth scaling by S.
 *
 *  AMAX    (output) DOUBLE PRECISION
 *          Absolute value of largest matrix element.  If AMAX is very
 *          close to overflow or very close to underflow, the matrix
 *          should be scaled.
 *
 *  INFO    (output) INTEGER
 *          = 0:  successful exit
 *          < 0:  if INFO = -i, the i-th argument had an illegal value
 *          > 0:  if INFO = i, the i-th diagonal element is nonpositive.

 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

Dpoequ()

Method Summary

static void

dpoequ(int n, double[] a, int _a_offset, int lda, double[] s, int _s_offset, doubleW scond, doubleW amax, intW info)

Methods inherited from class java.lang.Object

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

Constructor Detail

Dpoequ

public Dpoequ()

Method Detail

dpoequ

public static void dpoequ(int n,
                          double[] a,
                          int _a_offset,
                          int lda,
                          double[] s,
                          int _s_offset,
                          doubleW scond,
                          doubleW amax,
                          intW info)