de.lmu.ifi.dbs.elki.math

Class SinCosTable

java.lang.Object

de.lmu.ifi.dbs.elki.math.SinCosTable

Direct Known Subclasses:

SinCosTable.FullTable, SinCosTable.HalfTable, SinCosTable.QuarterTable

public abstract class SinCosTable
extends Object

Class to precompute / cache Sinus and Cosinus values. Note that the functions use integer offsets, not radians. TODO: add an interpolation function. TODO: add caching

Author:

Erich Schubert

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	SinCosTable.FullTable Table that can't exploit much symmetry, because the steps are not divisible by 2.
private static class	SinCosTable.HalfTable Table that exploits just one symmetry, as the number of steps is divisible by two.
private static class	SinCosTable.QuarterTable Table that exploits both symmetries, as the number of steps is divisible by four.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	steps Number of steps.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	SinCosTable(int steps) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
abstract double	cos(int step) Get Cosine by step value.
static SinCosTable	make(int steps) Make a table for the given number of steps.
abstract double	sin(int step) Get Sinus by step value.

Methods inherited from class java.lang.Object

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

Field Detail

steps

protected final int steps

Number of steps.

Constructor Detail

SinCosTable

private SinCosTable(int steps)

Constructor.

Parameters:

steps - Number of steps (ideally, steps % 4 = 0!)

Method Detail

cos

public abstract double cos(int step)

Get Cosine by step value.

Parameters:

step - Step value

Returns:

Cosinus

sin

public abstract double sin(int step)

Get Sinus by step value.

Parameters:

step - Step value

Returns:

Sinus

make

public static SinCosTable make(int steps)

Make a table for the given number of steps. For step numbers divisible by 4, an optimized implementation will be used.

Parameters:

steps - Number of steps

Returns:

Table