Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/**
 * Copyright 2008 - 2011
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 * 
 * @project loonframework
 * @author chenpeng
 * @emailceponline@yahoo.com.cn
 * @version 0.1
 */

public class Main {
    static final int AS1 = -1228;
    static final int AS2 = 4866;
    static final int AS3 = 13901;
    static final int AS4 = 102939;

    public static int acos(int f) {
        int fRoot = sqrt((1 << 16) - f);
        int result = AS1;
        result = mul(result, f);
        result += AS2;
        result = mul(result, f);
        result -= AS3;
        result = mul(result, f);
        result += AS4;
        result = mul(fRoot, result);
        return result;
    }

    static public final float acos(float value) {
        return (float) Math.acos(value);
    }

    public static int sqrt(int n) {
        int s = (n + 65536) >> 1;
        for (int i = 0; i < 8; i++) {
            s = (s + div(n, s)) >> 1;
        }
        return s;
    }

    static public final float sqrt(float a) {
        return (float) Math.sqrt(a);
    }

    public static int mul(int x, int y) {
        long z = (long) x * (long) y;
        return ((int) (z >> 16));
    }

    public static int div(int x, int y) {
        long z = (((long) x) << 32);
        return (int) ((z / y) >> 16);
    }
}