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Quaternion.cs
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Quaternion.cs
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//-----------------------------------------------------------------------
// <copyright file="Quaternion.cs" company="Math.NET Project">
// Copyright (c) 2002-2009, Christoph Rüegg.
// All Right Reserved.
// </copyright>
// <author>
// Christoph Rüegg, http://christoph.ruegg.name
// </author>
// <product>
// Math.NET Iridium, part of the Math.NET Project.
// http://mathnet.opensourcedotnet.info
// </product>
// <license type="opensource" name="LGPL" version="2 or later">
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2 of the License, or
// any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
// </license>
//-----------------------------------------------------------------------
using System;
using System.Text;
namespace MathNet.Numerics
{
/// <summary>Quaternion Number.</summary>
/// <remarks>
/// http://en.wikipedia.org/wiki/Quaternion
/// http://de.wikipedia.org/wiki/Quaternion
/// </remarks>
public struct Quaternion :
IComparable,
ICloneable
{
/* TODO: testing suite for Quaternion */
readonly double qw; // real part
readonly double qx, qy, qz; // imaginary part
readonly double qabs, qnorm; // norm
readonly double qarg; // polar notation
/// <summary>
/// Initializes a new instance of the Quaternion struct.
/// </summary>
public
Quaternion(
double real,
double imagX,
double imagY,
double imagZ)
{
qx = imagX;
qy = imagY;
qz = imagZ;
qw = real;
qnorm = ToNorm(real, imagX, imagY, imagZ);
qabs = Math.Sqrt(qnorm);
qarg = Math.Acos(real / qabs);
}
/// <summary>
/// Initializes a new instance of the Quaternion struct.
/// </summary>
internal
Quaternion(
double real,
double imagX,
double imagY,
double imagZ,
double abs,
double norm,
double arg)
{
qx = imagX;
qy = imagY;
qz = imagZ;
qw = real;
qnorm = norm;
qabs = abs;
qarg = arg;
}
static
double
ToNorm(
double real,
double imagX,
double imagY,
double imagZ)
{
return (imagX * imagX)
+ (imagY * imagY)
+ (imagZ * imagZ)
+ (real * real);
}
static
Quaternion
ToUnitQuaternion(
double real,
double imagX,
double imagY,
double imagZ)
{
double abs = Math.Sqrt(ToNorm(real, imagX, imagY, imagZ));
return new Quaternion(
real / abs,
imagX / abs,
imagY / abs,
imagZ / abs,
1, // abs
1, // norm
Math.Acos(real / abs)); // arg
}
#region Accessors
/// <summary>Gets the real part of the quaternion.</summary>
public double Real
{
get { return qw; }
}
/// <summary>Gets the imaginary X part (coefficient of complex I) of the quaternion.</summary>
public double ImagX
{
get { return qx; }
}
/// <summary>Gets the imaginary Y part (coefficient of complex J) of the quaternion.</summary>
public double ImagY
{
get { return qy; }
}
/// <summary>Gets the imaginary Z part (coefficient of complex K) of the quaternion.</summary>
public double ImagZ
{
get { return qz; }
}
/// <summary>G
/// ets the standard euclidean length |q| = sqrt(||q||) of the quaternion q: the square root of the sum of the squares of the four components.
/// Q may then be represented as q = r*(cos(phi) + u * sin(phi)) = r*exp(phi*u) where u is the unit vector and phi the argument of q.
/// </summary>
public double Abs
{
get { return qabs; }
}
/// <summary>Gets the norm ||q|| = |q|^2 of the quaternion q: the sum of the squares of the four components.</summary>
public double Norm
{
get { return qnorm; }
}
/// <summary>Gets the argument phi = arg(q) of the quaternion q, such that q = r*(cos(phi) + u * sin(phi)) = r*exp(phi*u) where r is the absolute and u the unit vector of q.</summary>
public double Arg
{
get { return qarg; }
}
/// <summary>True if the quaternion q is of lenght |q| = 1.</summary>
/// <remarks>To normalize a quaternion to a length of 1, use the <see cref="Sign"/> method. All unit quaternions form a 3-sphere.</remarks>
public bool IsUnitQuaternion
{
get { return Number.AlmostEqual(qabs, 1); }
}
/// <summary>
/// Returns a new Quaternion q with the Scalar part only.
/// If you need a Double, use the Real-Field instead.
/// </summary>
public
Quaternion
Scalar()
{
return new Quaternion(qw, 0, 0, 0);
}
/// <summary>
/// Returns a new Quaternion q with the Vectorpart only.
/// </summary>
public
Quaternion
Vector()
{
return new Quaternion(0, qx, qy, qz);
}
/// <summary>
/// Returns a new normalized Quaternion u with the Vectorpart only, such that ||u|| = 1.
/// Q may then be represented as q = r*(cos(phi) + u * sin(phi)) = r*exp(phi*u) where r is the absolute and phi the argument of q.
/// </summary>
public
Quaternion
UnitVector()
{
return ToUnitQuaternion(0, qx, qy, qz);
}
/// <summary>
/// Returns a new normalized Quaternion q with the direction of this quaternion.
/// </summary>
public
Quaternion
Sign()
{
return ToUnitQuaternion(qw, qx, qy, qz);
}
/////// <summary>
/////// Returns a new Quaternion q with the Sign of the components.
/////// </summary>
/////// <returns>
/////// <list type="bullet">
/////// <item>1 if Positive</item>
/////// <item>0 if Neutral</item>
/////// <item>-1 if Negative</item>
/////// </list>
/////// </returns>
////public Quaternion ComponentSigns()
////{
//// return new Quaternion(
//// Math.Sign(qx),
//// Math.Sign(qy),
//// Math.Sign(qz),
//// Math.Sign(qw));
////}
#endregion
#region Operators
/// <summary>
/// (nop)
/// </summary>
public static
Quaternion
operator +(Quaternion q)
{
return q;
}
/// <summary>
/// Negate a quaternion.
/// </summary>
public static
Quaternion
operator -(Quaternion q)
{
return q.Negate();
}
/// <summary>
/// Add a quaternion to a quaternion.
/// </summary>
public static
Quaternion
operator +(
Quaternion q1,
Quaternion q2)
{
return q1.Add(q2);
}
/// <summary>
/// Add a floating point number to a quaternion.
/// </summary>
public static
Quaternion
operator +(
Quaternion q1,
double d)
{
return q1.Add(d);
}
/// <summary>
/// Subtract a quaternion from a quaternion.
/// </summary>
public static
Quaternion
operator -(
Quaternion q1,
Quaternion q2)
{
return q1.Subtract(q2);
}
/// <summary>
/// Subtract a floating point number from a quaternion.
/// </summary>
public static
Quaternion
operator -(
Quaternion q1,
double d)
{
return q1.Subtract(d);
}
/// <summary>
/// Multiplay a quaternion with a quaternion.
/// </summary>
public static
Quaternion
operator *(
Quaternion q1,
Quaternion q2)
{
return q1.Multiply(q2);
}
/// <summary>
/// Multiplay a floating point number with a quaternion.
/// </summary>
public static
Quaternion
operator *(
Quaternion q1,
double d)
{
return q1.Multiply(d);
}
/// <summary>
/// Divide a quaternion by a quaternion.
/// </summary>
public static
Quaternion
operator /(
Quaternion q1,
Quaternion q2)
{
return q1.Divide(q2);
}
/// <summary>
/// Divide a quaternion by a floating point number.
/// </summary>
public static
Quaternion
operator /(
Quaternion q1,
double d)
{
return q1.Divide(d);
}
/// <summary>
/// Raise a quaternion to a quaternion.
/// </summary>
public static
Quaternion
operator ^(
Quaternion q1,
Quaternion q2)
{
return q1.Pow(q2);
}
/// <summary>
/// Raise a quaternion to a floating point number.
/// </summary>
public static
Quaternion
operator ^(
Quaternion q1,
double d)
{
return q1.Pow(d);
}
/// <summary>
/// Convert a floating point number to a quaternion.
/// </summary>
public static implicit
operator Quaternion(double d)
{
return new Quaternion(d, 0, 0, 0);
}
#endregion
#region Arithmetic Methods
/// <summary>
/// Add a quaternion to this quaternion.
/// </summary>
public
Quaternion
Add(Quaternion q)
{
return new Quaternion(
qw + q.qw,
qx + q.qx,
qy + q.qy,
qz + q.qz);
}
/// <summary>
/// Add a floating point number to this quaternion.
/// </summary>
public
Quaternion
Add(double r)
{
return new Quaternion(
qw + r,
qx,
qy,
qz);
}
/// <summary>
/// SUbtract a quaternion from this quaternion.
/// </summary>
public
Quaternion
Subtract(Quaternion q)
{
return new Quaternion(
qw - q.qw,
qx - q.qx,
qy - q.qy,
qz - q.qz);
}
/// <summary>
/// Subtract a floating point number from this quaternion.
/// </summary>
public
Quaternion
Subtract(double r)
{
return new Quaternion(
qw - r,
qx,
qy,
qz);
}
/// <summary>
/// Negate this quaternion.
/// </summary>
public
Quaternion
Negate()
{
return new Quaternion(
-qw,
-qx,
-qy,
-qz,
qabs, // abs
qnorm, // norm
Math.PI - qarg); // arg
}
/// <summary>
/// Multiply a quaternion with this quaternion.
/// </summary>
public
Quaternion
Multiply(Quaternion q)
{
double ci = (+qx * q.qw) + (qy * q.qz) - (qz * q.qy) + (qw * q.qx);
double cj = (-qx * q.qz) + (qy * q.qw) + (qz * q.qx) + (qw * q.qy);
double ck = (+qx * q.qy) - (qy * q.qx) + (qz * q.qw) + (qw * q.qz);
double cr = (-qx * q.qx) - (qy * q.qy) - (qz * q.qz) + (qw * q.qw);
return new Quaternion(cr, ci, cj, ck);
}
/// <summary>
/// Multiply a floating point number to this quaternion.
/// </summary>
public
Quaternion
Multiply(double d)
{
return new Quaternion(
d * qw,
d * qx,
d * qy,
d * qz);
}
/// <summary>
/// Multiplies a Quaternion with the inverse of another
/// Quaternion (q*q<sup>-1</sup>). Note that for Quaternions
/// q*q<sup>-1</sup> is not the same then q<sup>-1</sup>*q,
/// because this will lead to a rotation in the other direction.
/// </summary>
public
Quaternion
Divide(Quaternion q)
{
return Multiply(q.Inverse());
}
/// <summary>
/// Multiplies a Quaterion with the inverse of a real number.
/// </summary>
/// <remarks>
/// Its also Possible to cast a double to a Quaternion
/// and make the division afterwards. But this is less
/// performant.
/// </remarks>
public
Quaternion
Divide(double d)
{
return new Quaternion(
qw / d,
qx / d,
qy / d,
qz / d);
}
/// <summary>
/// Inverts this quaternion.
/// </summary>
public
Quaternion
Inverse()
{
if(Number.AlmostEqual(qabs, 1))
{
return new Quaternion(
qw,
-qx,
-qy,
-qz);
}
return new Quaternion(
qw / qnorm,
-qx / qnorm,
-qy / qnorm,
-qz / qnorm);
}
/// <summary>
/// Returns the distance |a-b| of two quaternions, forming a metric space.
/// </summary>
public static
double
Distance(
Quaternion a,
Quaternion b)
{
return a.Subtract(b).Abs;
}
/// <summary>
/// Conjugate this quaternion.
/// </summary>
public
Quaternion
Conjugate()
{
return new Quaternion(
qw,
-qx,
-qy,
-qz,
qabs,
qnorm,
qarg);
}
#endregion
#region Exponential
/// <summary>
/// Logarithm to a given base.
/// </summary>
public
Quaternion
Log(double lbase)
{
return Ln().Divide(Math.Log(lbase));
}
/// <summary>
/// Natural Logrithm to base E.
/// </summary>
public
Quaternion
Ln()
{
return UnitVector().Multiply(qarg).Add(Math.Log(qabs));
}
/// <summary>
/// Common Logarithm to base 10.
/// </summary>
public
Quaternion
Lg()
{
return Ln().Divide(Math.Log(10));
}
/// <summary>
/// Exponential Function.
/// </summary>
/// <returns></returns>
public
Quaternion
Exp()
{
double vabs = Math.Sqrt(ToNorm(0, qx, qy, qz));
return UnitVector().Multiply(Math.Sin(vabs)).Add(Math.Cos(vabs)).Multiply(Math.Exp(qw));
}
/// <summary>
/// Raise the quaternion to a given power.
/// </summary>
public
Quaternion
Pow(double power)
{
double arg = power * qarg;
return UnitVector().Multiply(Math.Sin(arg)).Add(Math.Cos(arg)).Multiply(Math.Pow(qw, power));
}
/// <summary>
/// Raise the quaternion to a given power.
/// </summary>
public
Quaternion
Pow(Quaternion power)
{
return power.Multiply(Ln()).Exp();
}
/// <summary>
/// Square of the Quaternion q: q^2.
/// </summary>
public
Quaternion
Sqr()
{
double arg = qarg * 2;
return UnitVector().Multiply(Math.Sin(arg)).Add(Math.Cos(arg)).Multiply(qw * qw);
}
/// <summary>
/// Square root of the Quaternion: q^(1/2).
/// </summary>
public
Quaternion
Sqrt()
{
double arg = qarg * 0.5;
return UnitVector().Multiply(Math.Sin(arg)).Add(Math.Cos(arg)).Multiply(Math.Sqrt(qw));
}
#endregion
#region Trigonometric
/* TODO: Implement */
#endregion
#region String Formatting and Parsing
/* TODO: Implement */
#endregion
#region .NET Integration: Hashing, Equality, Ordering, Cloning
/// <summary>
/// Compares this quaternion with another quaternion.
/// </summary>
public
int
CompareTo(object obj)
{
// TODO: Implement
throw new NotImplementedException();
}
/// <summary>
/// Creates a copy of this quaternion.
/// </summary>
public
object
Clone()
{
// TODO: Implement
throw new NotImplementedException();
}
#endregion
}
}