// <copyright file="GramSchmidt.cs" company="Math.NET">
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// Math.NET Numerics, part of the Math.NET Project
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// http://numerics.mathdotnet.com
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// http://github.com/mathnet/mathnet-numerics
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//
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// Copyright (c) 2009-2013 Math.NET
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// Software is furnished to do so, subject to the following
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// conditions:
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// included in all copies or substantial portions of the Software.
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// </copyright>
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using System;
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using IStation.Numerics.LinearAlgebra.Factorization;
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namespace IStation.Numerics.LinearAlgebra.Double.Factorization
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{
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/// <summary>
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/// <para>A class which encapsulates the functionality of the QR decomposition Modified Gram-Schmidt Orthogonalization.</para>
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/// <para>Any real square matrix A may be decomposed as A = QR where Q is an orthogonal mxn matrix and R is an nxn upper triangular matrix.</para>
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/// </summary>
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/// <remarks>
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/// The computation of the QR decomposition is done at construction time by modified Gram-Schmidt Orthogonalization.
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/// </remarks>
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internal abstract class GramSchmidt : GramSchmidt<double>
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{
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protected GramSchmidt(Matrix<double> q, Matrix<double> rFull)
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: base(q,rFull)
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{
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}
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/// <summary>
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/// Gets the absolute determinant value of the matrix for which the QR matrix was computed.
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/// </summary>
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public override double Determinant
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{
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get
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{
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if (FullR.RowCount != FullR.ColumnCount)
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{
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throw new ArgumentException("Matrix must be square.");
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}
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var det = 1.0;
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for (var i = 0; i < FullR.ColumnCount; i++)
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{
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det *= FullR.At(i, i);
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if (Math.Abs(FullR.At(i, i)).AlmostEqual(0.0))
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{
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return 0;
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}
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}
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return Convert.ToSingle(Math.Abs(det));
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}
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}
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/// <summary>
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/// Gets a value indicating whether the matrix is full rank or not.
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/// </summary>
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/// <value><c>true</c> if the matrix is full rank; otherwise <c>false</c>.</value>
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public override bool IsFullRank
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{
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get
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{
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for (var i = 0; i < FullR.ColumnCount; i++)
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{
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if (Math.Abs(FullR.At(i, i)).AlmostEqual(0.0))
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{
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return false;
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}
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}
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return true;
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}
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}
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}
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}
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