public static IEnumerable <Node> GetApproximatedPlotDataPoints(IFunction fun, Interval interval, int nodeCount,
ApproximationCriterium mode, out Polynomial approx)
{
var nodes = new List <Node>();
nodes.MakeNodes(interval, nodeCount);
var approximatingPolynomial = new Polynomial();
if (mode is ApproximationByPolynomialLevel)
{
var level = ((ApproximationByPolynomialLevel)mode).Level;
fun.EnableWeight = false;
approximatingPolynomial = mode.UseCotes
? GetApproxPolynomial(fun, level, NewNewtonCotes)
: GetApproxPolynomial(fun, level, LaguerreIntegration);
}
else
{
var i = 1;
var eps = ((ApproximationByAccuracy)mode).Accuracy;
var cache = new Dictionary <double, Polynomial>();
Func <IFunction, int, double> integratorFunc;
if (mode.UseCotes)
{
integratorFunc = NewNewtonCotes;
}
else
{
integratorFunc = LaguerreIntegration;
}
while (i++ < 20)
{
approximatingPolynomial = GetApproxPolynomial(fun, i, integratorFunc);
var error = GetError(fun, approximatingPolynomial);
if (error <= eps)
{
break;
}
cache.Add(error, new Polynomial {
Coefficients = approximatingPolynomial.Coefficients
});
}
if (i == 21)
{
approximatingPolynomial = cache.OrderBy(x => x.Key).First().Value; //choose lowest error
}
}
approx = approximatingPolynomial;
foreach (var t in nodes)
{
t.Y = approx.GetValue(t.X);
}
return(nodes);
}
