// Threadsafe
public double Eval(double x, double y)
{
double[] v = new double[factory.NTERMS];
factory.Basis(new XX(x, y), v, factory.NTERMS);
double r = 0;
for (int i = 0; i < factory.NTERMS; i++)
{
r += v[i] * coeff[i];
}
return(r);
}
public static Poly2D PolyFit2D(Poly2DFactory poly2dfactory, int NX, int NY, double[,] data, XX[,] pos)
{
int NPT = 0;
for (int i = 0; i < data.GetLength(0); i++)
{
for (int j = 0; j < data.GetLength(1); j++)
{
if (!Double.IsNaN(data[i, j]))
{
NPT++;
}
}
}
int NTERMS = poly2dfactory.NTERMS;
XX[] xx = new XX[NPT];
double[] z = new double[NPT]; // The function value at each point
double[] sig = new double[NPT]; // Measurement errors
// flatten: data -> z, pos -> xx
const float SIGMIN = 0.02f;
int rowno = 0;
for (int i = 0; i < NX; i++)
{
for (int j = 0; j < NY; j++)
{
if (Double.IsNaN(data[i, j]))
{
continue;
}
xx[rowno] = pos[i, j];
z[rowno] = data[i, j];
sig[rowno] = Math.Max(z[rowno] * SIGMIN, SIGMIN); // note that 1/sig[i] is used in FindFit
rowno++;
}
}
Debug.Assert(rowno == NPT);
// do the fit
double[] coeff, w;
double[,] u, v;
double chiSq;
FindFit(xx, z, sig, NTERMS, delegate(X _x, double[] _p, int _np) { poly2dfactory.Basis((XX)_x, _p, _np); }, out coeff, out u, out v, out w, out chiSq);
Debug.Assert(coeff.Length == NTERMS);
Debug.Assert(w.Length == NTERMS);
Debug.Assert((u.GetLength(0) == NPT) && (u.GetLength(1) == NTERMS));
Debug.Assert((v.GetLength(0) == NTERMS) && (v.GetLength(1) == NTERMS));
// calculate covariances
double[,] covar = null;
#if false // not used
covar = new double[NTERMS, NTERMS];
ComputeFitCovariance(v, NTERMS, w, covar);
#endif
return(new Poly2D(poly2dfactory, coeff, covar, chiSq));
}