Package net.algart.math.functions

Class MaxFromTwoSelectedNumbersFunc

java.lang.Object

net.algart.math.functions.AbstractFunc

net.algart.math.functions.MaxFromTwoSelectedNumbersFunc

All Implemented Interfaces:

Func

public class MaxFromTwoSelectedNumbersFunc
extends AbstractFunc
implements Func

Maximum from 2 arguments, selected by 1st argument: f(x₀, x₁, ..., x_n-1) = max(x_i+1, x_j+1), i=(int)x[0] (x₀ cast to integer type), j=(i−1+indexShift)%(n−1)+1, where indexShift is an integer constant, passed to getInstance(int) method.

More precisely, the get(double...) method of this object performs the following actions:

     int k1 = (int)x[0] + 1;
     // it is supposed that always 1<=(int)x[0]<=x.length
     int k2 = k1 + indexShift;
     if (k2 >= x.length) {
         // it is supposed that indexShift<x.length-1
         k2 -= x.length - 1;
     }
     return x[k1] > x[k2] ? x[k1] : x[k2];
 

If k1 or k2 index, calculated in such a way, is out of range 0..x.length-1, this method throws IndexOutOfBoundsException.

This function can be useful for algorithms of non-maximum suppression, usually in combination with Func.SELECT_FROM_8_DIRECTIONS_2D, for example, in algorithms like Canny edge detector.

This class is immutable and thread-safe: there are no ways to modify settings of the created instance.

Author:

Daniel Alievsky

Nested Class Summary

Nested classes/interfaces inherited from interface net.algart.math.functions.Func

Func.Updatable

Field Summary

Fields inherited from interface net.algart.math.functions.Func

ABS, ABS_DIFF, HALF_X_MINUS_Y, HALF_X_PLUS_Y, HALF_Y_MINUS_X, IDENTITY, MAX, MIN, POSITIVE_DIFF, REVERSE, SELECT, SELECT_FROM_8_DIRECTIONS_2D, SELECT_IF_GREATER, SELECT_IF_GREATER_OR_EQUAL, SHIFTS_ALONG_8_DIRECTIONS_2D, UPDATABLE_IDENTITY, X_MINUS_Y, X_PLUS_Y, Y_MINUS_X

Method Summary

Modifier and Type	Method	Description
double	get(double... x)	Returns the result of this function for the given arguments: f(x0, x1, ..., xx.length-1).
static MaxFromTwoSelectedNumbersFunc	getInstance(int indexShift)	Returns an instance of this class for the given index shift.
String	toString()	Returns a brief string description of this object.

Methods inherited from class net.algart.math.functions.AbstractFunc

get, get, get, get, get

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.algart.math.functions.Func

get, get, get, get, get

Method Details

getInstance

public static MaxFromTwoSelectedNumbersFunc getInstance(int indexShift)

Returns an instance of this class for the given index shift.

Parameters:

indexShift - the index shift (distance between compared numbers); must be non-negative.

Returns:

an instance of this class

Throws:

IllegalArgumentException - if indexShift<0.

get

public double get(double... x)

Description copied from interface: Func

Returns the result of this function for the given arguments: f(x₀, x₁, ..., x_x.length-1).

This method must not change the values of x elements!

Specified by:

get in interface Func

Specified by:

get in class AbstractFunc

Parameters:

x - the function arguments.

Returns:

the function result.

toString

public String toString()

Returns a brief string description of this object.

Overrides:

toString in class Object

Returns:

a brief string description of this object.