public void TestPosterior()
{
var logMath = LogMath.GetLogMath();
var lattice = new Lattice();
var a = lattice.AddNode("A", "A", 0, 0);
var b = lattice.AddNode("B", "B", 0, 0);
var c = lattice.AddNode("C", "C", 0, 0);
var d = lattice.AddNode("D", "D", 0, 0);
const double acousticAb = 4;
const double acousticAc = 6;
const double acousticCb = 1;
const double acousticBd = 5;
const double acousticCD = 2;
lattice.InitialNode = a;
lattice.TerminalNode = d;
lattice.AddEdge(a, b, logMath.LinearToLog(acousticAb), 0);
lattice.AddEdge(a, c, logMath.LinearToLog(acousticAc), 0);
lattice.AddEdge(c, b, logMath.LinearToLog(acousticCb), 0);
lattice.AddEdge(b, d, logMath.LinearToLog(acousticBd), 0);
lattice.AddEdge(c, d, logMath.LinearToLog(acousticCD), 0);
lattice.ComputeNodePosteriors(1.0f);
const double pathAbd = acousticAb * acousticBd;
const double pathAcbd = acousticAc * acousticCb * acousticBd;
const double pathAcd = acousticAc * acousticCD;
const double allPaths = pathAbd + pathAcbd + pathAcd;
const double bPosterior = (pathAbd + pathAcbd) / allPaths;
const double cPosterior = (pathAcbd + pathAcd) / allPaths;
const double delta = 1e-4;
Assert.AreEqual(logMath.LogToLinear((float)a.Posterior), 1.0, delta);
Assert.AreEqual(logMath.LogToLinear((float)b.Posterior), bPosterior, delta);
Assert.AreEqual(logMath.LogToLinear((float)c.Posterior), cPosterior, delta);
Assert.AreEqual(logMath.LogToLinear((float)d.Posterior), 1.0, delta);
}
