극저온 방사광 X-선 나노회절 기반 카고메 초전도체(CsV3Sb5) 전하밀도파(CDW) 및 네마틱 질서 파괴 능동 서보 아키텍처 (.NET 9 C# SIMD)

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

namespace ZeliDesk.Quantum.KagomeSuperconductors
{
    /// <summary>
    /// 카고메 초전도체(CsV3Sb5) CDW 및 네마틱 질서 능동 피에조 서보
    /// GC 무할당 ref struct 및 AVX-256 SIMD 가속화
    /// </summary>
    public ref struct KagomeCdwNematicityServo
    {
        private readonly ReadOnlySpan<float> _intensityH;       // 회절 피크 강도 I(h,0,l)
        private readonly ReadOnlySpan<float> _intensityK;       // 회절 피크 강도 I(0,k,l)
        private readonly Span<float> _nematicAsymmetries;       // 연산된 네마틱 비대칭도 eta
        private readonly Span<float> _piezoCorrectionVoltages;  // 피에조 능동 제어 전압 (V)

        private readonly float _targetAsymmetry; // 목표 비대칭도
        private readonly float _proportionalGain;// 비례 게인 K_p (V/unit)
        private readonly float _smallEps;        // 0 분모 방지 (1e-4f)

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public KagomeCdwNematicityServo(
            ReadOnlySpan<float> intensityH,
            ReadOnlySpan<float> intensityK,
            Span<float> nematicAsymmetries,
            Span<float> piezoCorrectionVoltages,
            float targetAsymmetry = 0.0f,
            float proportionalGain = 45.0f)
        {
            _intensityH = intensityH;
            _intensityK = intensityK;
            _nematicAsymmetries = nematicAsymmetries;
            _piezoCorrectionVoltages = piezoCorrectionVoltages;
            _targetAsymmetry = targetAsymmetry;
            _proportionalGain = proportionalGain;
            _smallEps = 1e-4f;
        }

        /// <summary>
        /// 8채널 회절 강도로부터 네마틱 비대칭도와 피에조 보정 전압을 SIMD 병렬 연산
        /// </summary>
        [MethodImpl(MethodImplOptions.AggressiveOptimization)]
        public void ProcessNematicityFeedback()
        {
            int length = _intensityH.Length;
            int simdLength = length - (length % 8);

            Vector256<float> vTarget = Vector256.Create(_targetAsymmetry);
            Vector256<float> vGain = Vector256.Create(_proportionalGain);
            Vector256<float> vEps = Vector256.Create(_smallEps);

            int i = 0;
            if (Avx2.IsSupported)
            {
                for (; i < simdLength; i += 8)
                {
                    Vector256<float> vIh = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_intensityH.Slice(i, 8))[0]);
                    Vector256<float> vIk = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_intensityK.Slice(i, 8))[0]);

                    // 분자: Ih - Ik
                    Vector256<float> vDiff = Avx.Subtract(vIh, vIk);
                    // 분모: Ih + Ik + eps
                    Vector256<float> vSum = Avx.Add(Avx.Add(vIh, vIk), vEps);

                    // 비대칭도 eta = (Ih - Ik) / (Ih + Ik + eps)
                    Vector256<float> vEta = Avx.Divide(vDiff, vSum);

                    // 편차: Error = eta - target
                    Vector256<float> vErr = Avx.Subtract(vEta, vTarget);

                    // 피에조 전압 지령 = -Gain * Error
                    Vector256<float> vPzt = Avx.Multiply(Avx.Subtract(Vector256<float>.Zero, vErr), vGain);

                    vEta.CopyTo(_nematicAsymmetries.Slice(i, 8));
                    vPzt.CopyTo(_piezoCorrectionVoltages.Slice(i, 8));
                }
            }

            for (; i < length; i++)
            {
                float diff = _intensityH[i] - _intensityK[i];
                float sum = _intensityH[i] + _intensityK[i] + _smallEps;
                float eta = diff / sum;
                float err = eta - _targetAsymmetry;
                _nematicAsymmetries[i] = eta;
                _piezoCorrectionVoltages[i] = -_proportionalGain * err;
            }
        }
    }
}