org.apache.commons.math3.transform

Class TransformUtils

java.lang.Object

org.apache.commons.math3.transform.TransformUtils

public class TransformUtils
extends java.lang.Object

Useful functions for the implementation of various transforms.

Since:

3.0

Field Summary

Fields

Modifier and Type	Field and Description
private static int[]	POWERS_OF_TWO Table of the powers of 2 to facilitate binary search lookup.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	TransformUtils() Private constructor.

Method Summary

Methods

Modifier and Type	Method and Description
static Complex[]	createComplexArray(double[][] dataRI) Builds a new array of Complex from the specified two dimensional array of real and imaginary parts.
static double[][]	createRealImaginaryArray(Complex[] dataC) Builds a new two dimensional array of double filled with the real and imaginary parts of the specified Complex numbers.
static int	exactLog2(int n) Returns the base-2 logarithm of the specified int.
static Complex[]	scaleArray(Complex[] f, double d) Multiply every component in the given complex array by the given real number.
static double[]	scaleArray(double[] f, double d) Multiply every component in the given real array by the given real number.

Methods inherited from class java.lang.Object

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

Field Detail

POWERS_OF_TWO

private static final int[] POWERS_OF_TWO

Table of the powers of 2 to facilitate binary search lookup.

See Also:

exactLog2(int)

Constructor Detail

TransformUtils

private TransformUtils()

Private constructor.

Method Detail

scaleArray

public static double[] scaleArray(double[] f,
                  double d)

Multiply every component in the given real array by the given real number. The change is made in place.

Parameters:

f - the real array to be scaled

d - the real scaling coefficient

Returns:

a reference to the scaled array

scaleArray

public static Complex[] scaleArray(Complex[] f,
                   double d)

Multiply every component in the given complex array by the given real number. The change is made in place.

Parameters:

f - the complex array to be scaled

d - the real scaling coefficient

Returns:

a reference to the scaled array

createRealImaginaryArray

public static double[][] createRealImaginaryArray(Complex[] dataC)

Builds a new two dimensional array of double filled with the real and imaginary parts of the specified Complex numbers. In the returned array dataRI, the data is laid out as follows

• dataRI[0][i] = dataC[i].getReal(),
• dataRI[1][i] = dataC[i].getImaginary().

Parameters:

dataC - the array of Complex data to be transformed

Returns:

a two dimensional array filled with the real and imaginary parts of the specified complex input

createComplexArray

public static Complex[] createComplexArray(double[][] dataRI)
                                    throws DimensionMismatchException

Builds a new array of Complex from the specified two dimensional array of real and imaginary parts. In the returned array dataC, the data is laid out as follows

• dataC[i].getReal() = dataRI[0][i],
• dataC[i].getImaginary() = dataRI[1][i].

Parameters:

dataRI - the array of real and imaginary parts to be transformed

Returns:

an array of Complex with specified real and imaginary parts.

Throws:

DimensionMismatchException - if the number of rows of the specified array is not two, or the array is not rectangular

exactLog2

public static int exactLog2(int n)
                     throws MathIllegalArgumentException

Returns the base-2 logarithm of the specified int. Throws an exception if n is not a power of two.

Parameters:

n - the int whose base-2 logarithm is to be evaluated

Returns:

the base-2 logarithm of n

Throws:

MathIllegalArgumentException - if n is not a power of two