public static string PolynomialFit(List <float[]> data)
{
int elements = data[0].Length - 1;
int samples = data.Count;
double[][] xy = new double[samples][];
double[] z = new double[samples];
for (int s = 0; s < samples; s++)
{
xy[s] = new double[elements];
for (int i = 0; i < elements; i++)
{
xy[s][i] = data[s][i + 1];
}
z[s] = data[s][0];
}
if (elements == 3)
{
double[] p = Fit.LinearMultiDim(xy, z,
d => 1.0,
d => d[0],
d => d[1],
d => d[2],
d => d[0] * d[1],
d => d[1] * d[2],
d => d[0] * d[2],
d => d[0] * d[1] * d[2]
);
return($"a+bX+cY+dI+eXY+fYI+gXI+hXYI,{p[0]},{p[1]},{p[2]},{p[3]},{p[4]},{p[5]},{p[6]},{p[7]}");
}
else if (elements == 2)
{
double[] p = Fit.LinearMultiDim(xy, z,
d => 1.0,
d => d[0],
d => d[1],
d => d[0] * d[1]
);
return($"a+bX+cY+dXY,{p[0]},{p[1]},{p[2]},{p[3]}");
}
else if (elements == 1)
{
double[] p = Fit.LinearMultiDim(xy, z,
d => 1.0,
d => d[0]
);
return($"a+bX,{p[0]},{p[1]}");
}
else if (elements == 0)
{
double[] p = Fit.LinearMultiDim(xy, z,
d => 1.0
);
return($"a,{p[0]}");
}
throw new ArgumentException();
}
