Package com.macrofocus.high_d.mds.pca

Class PCAMatrix

java.lang.Object

com.macrofocus.high_d.mds.pca.PCAMatrix

public class PCAMatrix
extends java.lang.Object

Constructor Summary

Constructors

Constructor	Description
PCAMatrix(double[][] A)	Construct a matrix from a 2-D array.
PCAMatrix(double[][] A, int m, int n)	Construct a matrix quickly without checking arguments.
PCAMatrix(double[] vals, int m)	Construct a matrix from a one-dimensional packed array
PCAMatrix(int m, int n)	Construct an m-by-n matrix of zeros.
PCAMatrix(int m, int n, double s)	Construct an m-by-n constant matrix.

Method Summary

Modifier and Type	Method	Description
PCAMatrix	copy()	Make a deep copy of a matrix
double	get(int i, int j)	Get a single element.
double[][]	getArray()	Access the internal two-dimensional array.
double[][]	getArrayCopy()	Copy the internal two-dimensional array.
int	getColumnDimension()	Get column dimension.
int	getRowDimension()	Get row dimension.
static double	hypot(double a, double b)	sqrt(a^2 + b^2) without under/overflow.
static PCAMatrix	identity(int m, int n)	Generate identity matrix
PCAMatrix	minus(PCAMatrix B)	C = A - B
static PCAMatrix	random(int m, int n)	Generate matrix with random elements
void	set(int i, int j, double s)	Set a single element.
PCAMatrix	times(double s)	Multiply a matrix by a scalar, C = s*A
PCAMatrix	times(PCAMatrix B)	Linear algebraic matrix multiplication, A * B
double	trace()	Matrix trace.
PCAMatrix	transpose()	Matrix transpose.

Methods inherited from class java.lang.Object

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

Constructor Detail

PCAMatrix

public PCAMatrix(int m,
                 int n)

Construct an m-by-n matrix of zeros.

Parameters:

m - Number of rows.

n - Number of colums.

PCAMatrix

public PCAMatrix(int m,
                 int n,
                 double s)

Construct an m-by-n constant matrix.

Parameters:

m - Number of rows.

n - Number of colums.

s - Fill the matrix with this scalar value.

PCAMatrix

public PCAMatrix(double[][] A)

Construct a matrix from a 2-D array.

Parameters:

A - Two-dimensional array of doubles.

Throws:

java.lang.IllegalArgumentException - All rows must have the same length

PCAMatrix

public PCAMatrix(double[][] A,
                 int m,
                 int n)

Construct a matrix quickly without checking arguments.

Parameters:

A - Two-dimensional array of doubles.

m - Number of rows.

n - Number of colums.

PCAMatrix

public PCAMatrix(double[] vals,
                 int m)

Construct a matrix from a one-dimensional packed array

Parameters:

vals - One-dimensional array of doubles, packed by columns (ala Fortran).

m - Number of rows.

Throws:

java.lang.IllegalArgumentException - Array length must be a multiple of m.

Method Detail

identity

public static PCAMatrix identity(int m,
                                 int n)

Generate identity matrix

Parameters:

m - Number of rows.

n - Number of colums.

Returns:

An m-by-n matrix with ones on the diagonal and zeros elsewhere.

getArray

public double[][] getArray()

Access the internal two-dimensional array.

Returns:

Pointer to the two-dimensional array of matrix elements.

random

public static PCAMatrix random(int m,
                               int n)

Generate matrix with random elements

Parameters:

m - Number of rows.

n - Number of colums.

Returns:

An m-by-n matrix with uniformly distributed random elements.

hypot

public static double hypot(double a,
                           double b)

sqrt(a^2 + b^2) without under/overflow.

copy

public PCAMatrix copy()

Make a deep copy of a matrix

getArrayCopy

public double[][] getArrayCopy()

Copy the internal two-dimensional array.

Returns:

Two-dimensional array copy of matrix elements.

getRowDimension

public int getRowDimension()

Get row dimension.

Returns:

m, the number of rows.

getColumnDimension

public int getColumnDimension()

Get column dimension.

Returns:

n, the number of columns.

get

public double get(int i,
                  int j)

Get a single element.

Parameters:

i - Row index.

j - Column index.

Returns:

A(i, j)

Throws:

java.lang.ArrayIndexOutOfBoundsException

set

public void set(int i,
                int j,
                double s)

Set a single element.

Parameters:

i - Row index.

j - Column index.

s - A(i,j).

Throws:

java.lang.ArrayIndexOutOfBoundsException

times

public PCAMatrix times(double s)

Multiply a matrix by a scalar, C = s*A

Parameters:

s - scalar

Returns:

s*A

minus

public PCAMatrix minus(PCAMatrix B)

C = A - B

Parameters:

B - another matrix

Returns:

A - B

times

public PCAMatrix times(PCAMatrix B)

Linear algebraic matrix multiplication, A * B

Parameters:

B - another matrix

Returns:

Matrix product, A * B

Throws:

java.lang.IllegalArgumentException - Matrix inner dimensions must agree.

trace

public double trace()

Matrix trace.

Returns:

sum of the diagonal elements.

transpose

public PCAMatrix transpose()

Matrix transpose.

Returns:

A'