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/*
* The MIT License (MIT)
*
* Copyright (c) 2015 Camil Staps <info@camilstaps.nl>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package com.camilstaps.mandelbrot;
import java.util.HashMap;
import java.util.Map;
/**
* Class for calculating Mandelbrot numbers
* By remembering seen numbers, we can significantly decrease calculation time
*
* @author Camil Staps
*/
public class MandelbrotFractal {
/**
* Storage for previously calculated numbers
*/
private static final Map<Point,Result> mandelNumbers = new HashMap<>();
public static int mandelNumber(double x, double y, int repetitions) {
Point p = new Point(x, y);
return mandelNumber(p, repetitions);
}
public static int mandelNumber(Point p, int repetitions) {
if (mandelNumbers.containsKey(p)) {
Result result = mandelNumbers.get(p);
if (repetitions < result.repetitions ||
result.mandelNumber < result.repetitions) {
return result.mandelNumber;
} else {
calculateMandelNumber(p, repetitions, result);
return result.mandelNumber;
}
} else {
Result result = calculateMandelNumber(p, repetitions);
mandelNumbers.put(p, result);
return result.mandelNumber;
}
}
protected static Result calculateMandelNumber(Point p, int repetitions) {
Result start = new Result();
start.x = p.x;
start.y = p.y;
calculateMandelNumber(p, repetitions, start);
return start;
}
protected static void calculateMandelNumber(Point p, int repetitions, Result start) {
int n = start.repetitions;
while (start.x * start.x + start.y * start.y <= 4 && n < repetitions) {
double new_x = start.x * start.x - start.y * start.y + p.x;
start.y = 2 * start.x * start.y + p.y;
start.x = new_x;
n++;
}
start.mandelNumber = n;
}
public static class Point {
double x, y;
public Point(double x, double y) {
this.x = x;
this.y = y;
}
@Override
public boolean equals(Object another) {
if (another == null || another.getClass() != Point.class) {
return false;
}
Point that = (Point) another;
return that.x == x && that.y == y;
}
@Override
public int hashCode() {
int hash = 7;
hash = 97 * hash + (int) (Double.doubleToLongBits(this.x) ^ (Double.doubleToLongBits(this.x) >>> 32));
hash = 97 * hash + (int) (Double.doubleToLongBits(this.y) ^ (Double.doubleToLongBits(this.y) >>> 32));
return hash;
}
@Override
public String toString() {
return String.format("(%f,%f)", x, y);
}
}
protected static class Result {
int mandelNumber = -1, repetitions = 0;
double x, y;
}
}
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