org.netlib.lapack
Class SPPEQU
java.lang.Object
org.netlib.lapack.SPPEQU
public class SPPEQU
 extends java.lang.Object
SPPEQU is a simplified interface to the JLAPACK routine sppequ.
This interface converts Javastyle 2D rowmajor arrays into
the 1D columnmajor 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
* =======
*
* SPPEQU computes row and column scalings intended to equilibrate a
* symmetric positive definite matrix A in packed storage and reduce
* its condition number (with respect to the twonorm). 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
* =========
*
* UPLO (input) CHARACTER*1
* = 'U': Upper triangle of A is stored;
* = 'L': Lower triangle of A is stored.
*
* N (input) INTEGER
* The order of the matrix A. N >= 0.
*
* AP (input) REAL array, dimension (N*(N+1)/2)
* The upper or lower triangle of the symmetric matrix A, packed
* columnwise in a linear array. The jth column of A is stored
* in the array AP as follows:
* if UPLO = 'U', AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j;
* if UPLO = 'L', AP(i + (j1)*(2nj)/2) = A(i,j) for j<=i<=n.
*
* S (output) REAL array, dimension (N)
* If INFO = 0, S contains the scale factors for A.
*
* SCOND (output) REAL
* 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) REAL
* 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 ith argument had an illegal value
* > 0: if INFO = i, the ith diagonal element is nonpositive.
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
SPPEQU(java.lang.String uplo,
int n,
float[] ap,
float[] s,
floatW scond,
floatW amax,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
SPPEQU
public SPPEQU()
SPPEQU
public static void SPPEQU(java.lang.String uplo,
int n,
float[] ap,
float[] s,
floatW scond,
floatW amax,
intW info)