using System;

namespace Science.Physics.GeneralPhysics
{
	/// <summary>
	/// Sound
	/// </summary>
	public class Sound
	{
		public Sound()
		{
		}
		private double v = 343; // at t=20C
		public double TypicalSpeed  
		{
			get{return v;}
			set{v=value;}
		}
		public void SetSpeed(Temperature t)
		{
			v = 331.0*Math.Sqrt(1.0+t.C/273.0);
		}
		public double Speed(Elasticity e, Density rho)
		{
			return Math.Sqrt(e.BulkModulus/rho.kgPERmCUBE);
		}
		public void DopplerEffect(Frequency source, Speed vs,
			Frequency observer, Speed vo)
		{
			if(source.VariableQ) source.Hz = observer.Hz*(v-vs.mPERs)/(v+vo.mPERs);
			else if(vs.VariableQ) vs.mPERs = v - (v+vo.mPERs)*source.Hz/observer.Hz;
			else if(observer.VariableQ) observer.Hz = (v+vo.mPERs)/(v-vs.mPERs)*source.Hz;
			else vo.mPERs =  -v + (v-vs.mPERs)/source.Hz*observer.Hz;
		}
		private double I;
		public double Intensity
		{
			get{return I;}
			set{I = value;}
		}
		public double dB
		{
			get{return 10.0*Math.Log10(I/1.0E-12);}
		}
	}
}