rg1/server/Sog/Core/Math/Math.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;



namespace Sog
{
    public static class MathUtils
    {
        public static int MAX_RAND_RANGE = 10000;

        private static long CHIP_LEVEL_1 = 1000000;

        // 从[min, max]中随机取need个整数，need大于区间长度时，返回数中出现重复数字
        public static List<int> GetRandomList(int min, int max, int need)
        {
            int range = max - min + 1;
            if (range <= 0 || range > MAX_RAND_RANGE)
            {
                TraceLog.Error("MathUtils.GetRandomList range {0} is great than max {1}", range, MAX_RAND_RANGE);
                return new List<int>();
            }

            var list = new List<int>(range);
            for (int i = 0; i < range; i++)
            {
                list.Add(min + i);
            }

            var rand = new Random();
            var ret = new List<int>(need);
            int size = range;

            for (int i = 0; i < need; i++)
            {
                if (size == 0)
                {
                    size = range;
                }

                int idx = rand.Next(size);
                ret.Add(list[idx]);

                int tmp = list[idx];
                list[idx] = list[size - 1];
                list[size - 1] = tmp;

                size--;
            }

            return ret;
        }

        public static string NumberToStringTK(long num)
        {
            bool negative = false;
            if (num < 0)
            {
                negative = true;
                num = -num;
            }

            string output = "";
            long integerPart = num;

            // 超过1000000的以M为单位显示，小数点后最多显示2位，如1.68M
            if (num >= CHIP_LEVEL_1)
            {
                integerPart = num / CHIP_LEVEL_1;
                long fractionalPart = num % CHIP_LEVEL_1;
                fractionalPart = fractionalPart / 10000;
                if (fractionalPart > 0)
                {
                    output = string.Format(",{0:D2}M", fractionalPart);
                }
                else
                {
                    output = "M";
                }
            }

            // 剩余整数部分每3位以"."分格，如123456789012345 = 123.456.789,01M
            while (integerPart >= 1000)
            {
                long tmp = integerPart / 1000;
                long remain = integerPart % 1000;
                output = string.Format(".{0:D3}{1}", remain, output);
                integerPart = tmp;
            }

            output = string.Format("{0}{1}", integerPart, output);

            if (negative)
            {
                output = "-" + output;
            }

            return output;
        }

        public static double Erf(double x)
        {
            // constants
            double a1 = 0.254829592;
            double a2 = -0.284496736;
            double a3 = 1.421413741;
            double a4 = -1.453152027;
            double a5 = 1.061405429;
            double p = 0.3275911;

            // Save the sign of x
            int sign = 1;
            if (x < 0)
                sign = -1;
            x = Math.Abs(x);

            // A&S formula 7.1.26
            double t = 1.0 / (1.0 + p * x);
            double y = 1.0 - (((((a5 * t + a4) * t) + a3) * t + a2) * t + a1) * t * Math.Exp(-x * x);

            return sign * y;
        }

        public static string FormatNumber(long num, int decimals = 2)
        {
            double exponent = 0;
            string formatNum;

            if (decimals > 0)
            {
                exponent = Math.Pow(10, decimals);
            }


            if (num > 999999999999)
            {
                var resullt = Math.Floor(num * 1.0 / 1000000000000 * exponent) / exponent;
                formatNum = resullt.ToString() + "T";
            }
            else if (num > 999999999)
            {
                var resullt = Math.Floor(num * 1.0 / 1000000000 * exponent) / exponent;
                formatNum = resullt.ToString() + "B";
            }
            else if (num > 999999)
            {
                var resullt = Math.Floor(num * 1.0 / 1000000 * exponent) / exponent;
                formatNum = resullt.ToString() + "M";
            }
            else if (num > 9999)
            {
                var resullt = Math.Floor(num * 1.0 / 1000 * exponent) / exponent;
                formatNum = resullt.ToString() + "K";
            }
            else
            {
                formatNum = num.ToString();
            }


            return formatNum;

        }

        //快速平方根算法
        unsafe public static double FastSqrtIEEE(double number)
        {
            long i;
            double x, y;
            const double threehalfs = 1.5f;
            y = number;
            x = number * 0.5f;

            i = *(long*)&y;

            i = 0x5fe6ec85e7de30daL - (i >> 1);

            y = *(double*)&i;

            y *= threehalfs - (x * y * y);
            y *= threehalfs - (x * y * y);

            return number * y;
        }
    }
}