public static double evaluateLagrangePolynome(double x, Vector nodes, int j)
{
int idx;
//Gibt die Position zurück, wenn x einer Stützerstelle entspricht.
if ((idx = nodes.ContainsValue(x)) != -1)
{
if (idx == j)
return 1.0;
else
return 0.0;
}
Vector barycentricWeights = computeBarycentricWeights(nodes);
double tempProd = 1.0;
for(int i = 0; i < nodes.Length; i++)
{
if (i != j)
tempProd *= (x - nodes[i]);
}
tempProd *= barycentricWeights[j];
return tempProd;
}
public static double evaluateLagrangeRepresentation(double x, Vector nodes, Vector functionValues)
{
int idx;
//Gibt die Position zurück, wenn x einer Stützerstelle entspricht.
if( (idx = nodes.ContainsValue(x)) != -1)
return functionValues[idx];
Vector barycentricWeights = computeBarycentricWeights(nodes);
double tempQuot = 0.0;
double denominator = 0.0;
double numerator = 0.0;
for(int i = 0; i < nodes.Length; i++)
{
tempQuot = barycentricWeights[i] / (x - nodes[i]);
numerator += functionValues[i] * tempQuot;
denominator += tempQuot;
}
return numerator / denominator;
}
