java.lang.Object
- org.apache.commons.statistics.inference.SquareMatrixSupport.ArrayRealSquareMatrix

All Implemented Interfaces:

SquareMatrixSupport.RealSquareMatrix

Enclosing class:

SquareMatrixSupport
```
private static class SquareMatrixSupport.ArrayRealSquareMatrix
extends java.lang.Object
implements SquareMatrixSupport.RealSquareMatrix
```
Implementation of SquareMatrixSupport.RealSquareMatrix using a double[] array to store entries. Values are addressed using i*dim + j where dim is the square dimension.
Scaling is supported using the central element [m][m] where m = dimension/2. Scaling is only implemented post-multiplication to protect against overflow during repeat multiplication operations.
Note: The scaling is implemented to support computation of Kolmogorov's distribution as described in:
- Marsaglia, G., Tsang, W. W., & Wang, J. (2003). Evaluating Kolmogorov's Distribution. Journal of Statistical Software, 8(18), 1–4.

Field Summary

Fields
Modifier and Type	Field	Description
`private double[]`	`data`	Entries of the matrix.
`private int`	`dim`	Dimension.
`private int`	`exp`	Matrix scale.
`private static double`	`SCALE_THRESHOLD`	The scaling threshold.

Constructor Summary

Constructors
Constructor Description

ArrayRealSquareMatrix(int dimension, double[] data, int scale)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private static void`	`checkExponent(int p)`	Check the exponent is not negative.
`int`	`dimension()`	Gets the dimension for the rows and columns.
`double`	`get(int i, int j)`	Gets the value.
`private SquareMatrixSupport.RealSquareMatrix`	`identity()`	Creates the identity matrix I with the same dimension as `this`.
`private static int`	`multiply(double[] a, int sa, double[] b, int sb, double[] col, double[] out)`	Returns the result of postmultiplying `a` by `b`.
`SquareMatrixSupport.RealSquareMatrix`	`power(int n)`	Returns the result of multiplying `this` with itself `n` times.
`int`	`scale()`	Gets the scale of the matrix values.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - SCALE_THRESHOLD
```
private static final double SCALE_THRESHOLD
```
    The scaling threshold. Marsaglia used 1e140. This uses 2^400 ~ 2.58e120
    
    See Also:
    
    Constant Field Values
  - dim
```
private final int dim
```
    Dimension.
  - data
```
private final double[] data
```
    Entries of the matrix.
  - exp
```
private final int exp
```
    Matrix scale.
- Constructor Detail
  - ArrayRealSquareMatrix
```
ArrayRealSquareMatrix(int dimension,
                      double[] data,
                      int scale)
```
    Parameters:
    
    dimension - Matrix dimension.
    
    data - Matrix data.
    
    scale - Matrix scale.
- Method Detail
  - dimension
```
public int dimension()
```
    Description copied from interface: SquareMatrixSupport.RealSquareMatrix
    
    Gets the dimension for the rows and columns.
    
    Specified by:
    
    dimension in interface SquareMatrixSupport.RealSquareMatrix
    
    Returns:
    
    the dimension
  - scale
```
public int scale()
```
    Description copied from interface: SquareMatrixSupport.RealSquareMatrix
    
    Gets the scale of the matrix values. The true value is the value returned from SquareMatrixSupport.RealSquareMatrix.get(int, int) multiplied by 2^scale.
    
    Specified by:
    
    scale in interface SquareMatrixSupport.RealSquareMatrix
    
    Returns:
    
    the scale
  - get
```
public double get(int i,
                  int j)
```
    Description copied from interface: SquareMatrixSupport.RealSquareMatrix
    
    Gets the value. This is a scaled value. The true value is the value returned multiplied by 2^scale.
    
    Specified by:
    
    get in interface SquareMatrixSupport.RealSquareMatrix
    
    Parameters:
    
    i - Row
    
    j - Column
    
    Returns:
    
    the value
    
    See Also:
    
    SquareMatrixSupport.RealSquareMatrix.scale()
  - power
```
public SquareMatrixSupport.RealSquareMatrix power(int n)
```
    Description copied from interface: SquareMatrixSupport.RealSquareMatrix
    
    Returns the result of multiplying this with itself n times.
    
    Specified by:
    
    power in interface SquareMatrixSupport.RealSquareMatrix
    
    Parameters:
    
    n - raise this to power n
    
    Returns:
    
    this^n
  - identity
```
private SquareMatrixSupport.RealSquareMatrix identity()
```
    Creates the identity matrix I with the same dimension as this.
    
    Returns:
    
    I
  - multiply
```
private static int multiply(double[] a,
                            int sa,
                            double[] b,
                            int sb,
                            double[] col,
                            double[] out)
```
    Returns the result of postmultiplying a by b. It is expected the scale of the result will be the sum of the scale of the arguments; this may be adjusted by the scale power if the result is scaled by a power of two for overflow protection.
    
    Parameters:
    
    a - Matrix.
    
    sa - Scale of matrix a.
    
    b - Matrix to postmultiply by.
    
    sb - Scale of matrix b.
    
    col - Working array for a column of the matrix.
    
    out - Output a * b
    
    Returns:
    
    Scale of a * b
  - checkExponent
```
private static void checkExponent(int p)
```
    Check the exponent is not negative.
    
    Parameters:
    
    p - Exponent.
    
    Throws:
    
    java.lang.IllegalArgumentException - if the exponent is negative

Class SquareMatrixSupport.ArrayRealSquareMatrix

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SCALE_THRESHOLD

dim

data

exp

Constructor Detail

ArrayRealSquareMatrix

Method Detail

dimension

scale

get

power

identity

multiply

checkExponent