//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="ATan"
// Project: StgSharp
// AuthorGroup: Nitload
// Copyright (c) Nitload. All rights reserved.
//     
// 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.
//     
// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using System;
using System.Runtime.CompilerServices;

namespace StgSharp.Mathematics
{
    public static unsafe partial class Scalar
    {

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static unsafe float ATan(float x)
        {
            return MathF.Atan(x);
            /*
            float sign = 1, angle = 0;
            if (x < 0)
            {
                sign = -1;
                x = -x;
            }
            uint xBit = *(uint*)&x;
            int xExp = (int)(xBit >> 23) - 127;
            if (xExp >= 26)
            {
                return 1;
            }
            if (xExp <= -15)
            {
                return x;
            }
            if (xExp >= 0)
            {
                x = (x - 1) / (x + 1);
                angle = 0.7853981634f;
            }

            float vec = 0.7853981634f * x + x * (1 - x) * (0.2447f + 0.0663f * x);
            vec += angle;
            vec *= sign;

            return vec;


        }


        public static unsafe float ATan(float x, float y)
        {


            float z = y / x;

            float sign = 1, angle = 0, angle2 = 0;
            if (x < 0)
            {
                angle = -3.1415926535f;
            }
            if (z < 0)
            {
                sign = -1;
                z = -z;
            }
            uint zBit = *(uint*)&z;
            int zExp = (int)(zBit >> 23) - 127;
            if (zExp >= 26)
            {
                return 1;
            }
            if (zExp <= -15)
            {
                return z;
            }
            if (zExp >= 0)
            {
                z = (z - 1) / (z + 1);
                angle2 = 0.7853981634f;
            }

            float vec = 0.7853981634f * z + z * (1 - z) * (0.2447f + 0.0663f * z);
            vec *= 57.29577951f;
            vec += angle2;
            vec += angle;
            vec *= sign;

            return vec;
            */
        }

    }
}