Determinant.cs

using System;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Functions.Vectors;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Functions.Matrices
{
    public class Determinant : FunctionOneVariable
    {
        public Determinant(ScriptNode Argument, int Start, int Length, Expression Expression)
            : base(Argument, Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(Determinant);
 
        public override string[] Aliases => new string[] { "det" };
 
        public override IElement Evaluate(IElement Argument, Variables Variables)
        {
            if (Argument is IMatrix M)
            {
                int N = M.Columns;
                if (N != M.Rows)
                    throw new ScriptRuntimeException("Expected square matrix argument.", this);
 
                IMatrix M2 = M.Reduce(false, true, out int Rank, out ICommutativeRingWithIdentityElement Factor);
                if (M2 is null || Rank < N || Factor is null)
                    return Factor?.Zero ?? new DoubleNumber(0);
                else
                    return Factor;
            }
            else
                throw new ScriptRuntimeException("Expected matrix argument.", this);
        }
    }
}