using System;
using System.Runtime.CompilerServices;

namespace MTAssets.UltimateLODSystem.MeshSimplifier
{
	public struct SymmetricMatrix
	{
		public double m0;

		public double m1;

		public double m2;

		public double m3;

		public double m4;

		public double m5;

		public double m6;

		public double m7;

		public double m8;

		public double m9;

		public double this[int index]
		{
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			get
			{
				return index switch
				{
					0 => m0, 
					1 => m1, 
					2 => m2, 
					3 => m3, 
					4 => m4, 
					5 => m5, 
					6 => m6, 
					7 => m7, 
					8 => m8, 
					9 => m9, 
					_ => throw new ArgumentOutOfRangeException("index"), 
				};
			}
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public SymmetricMatrix(double c)
		{
			m0 = c;
			m1 = c;
			m2 = c;
			m3 = c;
			m4 = c;
			m5 = c;
			m6 = c;
			m7 = c;
			m8 = c;
			m9 = c;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public SymmetricMatrix(double m0, double m1, double m2, double m3, double m4, double m5, double m6, double m7, double m8, double m9)
		{
			this.m0 = m0;
			this.m1 = m1;
			this.m2 = m2;
			this.m3 = m3;
			this.m4 = m4;
			this.m5 = m5;
			this.m6 = m6;
			this.m7 = m7;
			this.m8 = m8;
			this.m9 = m9;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public SymmetricMatrix(double a, double b, double c, double d)
		{
			m0 = a * a;
			m1 = a * b;
			m2 = a * c;
			m3 = a * d;
			m4 = b * b;
			m5 = b * c;
			m6 = b * d;
			m7 = c * c;
			m8 = c * d;
			m9 = d * d;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public static SymmetricMatrix operator +(SymmetricMatrix a, SymmetricMatrix b)
		{
			return new SymmetricMatrix(a.m0 + b.m0, a.m1 + b.m1, a.m2 + b.m2, a.m3 + b.m3, a.m4 + b.m4, a.m5 + b.m5, a.m6 + b.m6, a.m7 + b.m7, a.m8 + b.m8, a.m9 + b.m9);
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		internal double Determinant1()
		{
			return m0 * m4 * m7 + m2 * m1 * m5 + m1 * m5 * m2 - m2 * m4 * m2 - m0 * m5 * m5 - m1 * m1 * m7;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		internal double Determinant2()
		{
			return m1 * m5 * m8 + m3 * m4 * m7 + m2 * m6 * m5 - m3 * m5 * m5 - m1 * m6 * m7 - m2 * m4 * m8;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		internal double Determinant3()
		{
			return m0 * m5 * m8 + m3 * m1 * m7 + m2 * m6 * m2 - m3 * m5 * m2 - m0 * m6 * m7 - m2 * m1 * m8;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		internal double Determinant4()
		{
			return m0 * m4 * m8 + m3 * m1 * m5 + m1 * m6 * m2 - m3 * m4 * m2 - m0 * m6 * m5 - m1 * m1 * m8;
		}

		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public double Determinant(int a11, int a12, int a13, int a21, int a22, int a23, int a31, int a32, int a33)
		{
			return this[a11] * this[a22] * this[a33] + this[a13] * this[a21] * this[a32] + this[a12] * this[a23] * this[a31] - this[a13] * this[a22] * this[a31] - this[a11] * this[a23] * this[a32] - this[a12] * this[a21] * this[a33];
		}
	}
}