org.jblas
Class Geometry

java.lang.Object
  extended by org.jblas.Geometry

public class Geometry
extends java.lang.Object

General functions which are geometric in nature.

For example, computing all pairwise squared distances between all columns of a matrix.


Constructor Summary
Geometry()
           
 
Method Summary
static DoubleMatrix center(DoubleMatrix x)
          Center a vector (subtract mean from all elements (in-place).
static FloatMatrix center(FloatMatrix x)
          Center a vector (subtract mean from all elements (in-place).
static DoubleMatrix centerColumns(DoubleMatrix x)
          Center the columns of a matrix (in-place).
static FloatMatrix centerColumns(FloatMatrix x)
          Center the columns of a matrix (in-place).
static DoubleMatrix centerRows(DoubleMatrix x)
          Center the rows of a matrix (in-place).
static FloatMatrix centerRows(FloatMatrix x)
          Center the rows of a matrix (in-place).
static DoubleMatrix normalize(DoubleMatrix x)
          Normalize a vector (scale such that its Euclidean norm is 1) (in-place).
static FloatMatrix normalize(FloatMatrix x)
          Normalize a vector (scale such that its Euclidean norm is 1) (in-place).
static DoubleMatrix normalizeColumns(DoubleMatrix x)
          Normalize the columns of a matrix (in-place).
static FloatMatrix normalizeColumns(FloatMatrix x)
          Normalize the columns of a matrix (in-place).
static DoubleMatrix normalizeRows(DoubleMatrix x)
          Normalize the rows of a matrix (in-place).
static FloatMatrix normalizeRows(FloatMatrix x)
          Normalize the rows of a matrix (in-place).
static DoubleMatrix pairwiseSquaredDistances(DoubleMatrix X, DoubleMatrix Y)
          Compute the pairwise squared distances between all columns of the two matrices.
static FloatMatrix pairwiseSquaredDistances(FloatMatrix X, FloatMatrix Y)
          Compute the pairwise squared distances between all columns of the two matrices.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Geometry

public Geometry()
Method Detail

pairwiseSquaredDistances

public static DoubleMatrix pairwiseSquaredDistances(DoubleMatrix X,
                                                    DoubleMatrix Y)

Compute the pairwise squared distances between all columns of the two matrices.

An efficient way to do this is to observe that (x-y)^2 = x^2 - 2xy - y^2 and to then properly carry out the computation with matrices.


center

public static DoubleMatrix center(DoubleMatrix x)
Center a vector (subtract mean from all elements (in-place).


centerRows

public static DoubleMatrix centerRows(DoubleMatrix x)
Center the rows of a matrix (in-place).


centerColumns

public static DoubleMatrix centerColumns(DoubleMatrix x)
Center the columns of a matrix (in-place).


normalize

public static DoubleMatrix normalize(DoubleMatrix x)
Normalize a vector (scale such that its Euclidean norm is 1) (in-place).


normalizeRows

public static DoubleMatrix normalizeRows(DoubleMatrix x)
Normalize the rows of a matrix (in-place).


normalizeColumns

public static DoubleMatrix normalizeColumns(DoubleMatrix x)
Normalize the columns of a matrix (in-place).


pairwiseSquaredDistances

public static FloatMatrix pairwiseSquaredDistances(FloatMatrix X,
                                                   FloatMatrix Y)

Compute the pairwise squared distances between all columns of the two matrices.

An efficient way to do this is to observe that (x-y)^2 = x^2 - 2xy - y^2 and to then properly carry out the computation with matrices.


center

public static FloatMatrix center(FloatMatrix x)
Center a vector (subtract mean from all elements (in-place).


centerRows

public static FloatMatrix centerRows(FloatMatrix x)
Center the rows of a matrix (in-place).


centerColumns

public static FloatMatrix centerColumns(FloatMatrix x)
Center the columns of a matrix (in-place).


normalize

public static FloatMatrix normalize(FloatMatrix x)
Normalize a vector (scale such that its Euclidean norm is 1) (in-place).


normalizeRows

public static FloatMatrix normalizeRows(FloatMatrix x)
Normalize the rows of a matrix (in-place).


normalizeColumns

public static FloatMatrix normalizeColumns(FloatMatrix x)
Normalize the columns of a matrix (in-place).



written by Mikio L. Braun and Johannes Schaback