// Values
double[] getK(List <double[]> list)
{
double[] K = { };
if (list.Count == 2)
{
// Polynomial Curve: dY = dX * ( K0 * (X0 + X1) + K1 )
K = new double[] { 0, (list[1][1] - list[0][1]) / (list[1][0] - list[0][0]) };
curve = Ktype.Polynomial;
return(K);
}
double[] dY = { list[list.Count - 2][1] - list[list.Count - 3][1], list[list.Count - 1][1] - list[list.Count - 2][1] };
double[] dX = { list[list.Count - 2][0] - list[list.Count - 3][0], list[list.Count - 1][0] - list[list.Count - 2][0] };
double curvature = (dY[1] / dX[1] - dY[0] / dX[0]) / ((dX[0] + dX[1]) / 2);
if (curvature > 0)
{
// Exponential Curve: Y1/Y0 = EXP(dX * K);
K = new double[] { Math.Log(list.Last()[1] / list[list.Count - 2][1]) / dX[1] };
curve = Ktype.Exponential;
}
else if (curvature < 0 && dY[1] >= 0)
{
// Logarithmic Curve: dY = K * LN(X1/X0);
K = new double[] { dY[1] / Math.Log(list.Last()[0] / list[list.Count - 2][0]) };
curve = Ktype.Logarithmic;
}
else
{
// Polynomial Curve: dY = dX * ( K0 * (X0 + X1) + K1 )
K = new double[] { curvature / 2, dY[1] / dX[1] - (list.Last()[0] + list[list.Count - 2][0]) * curvature / 2 };
curve = Ktype.Polynomial;
}
return(K);
}
// Values
double[] getK(List<double[]> list)
{
double[] K = { };
if (list.Count == 2)
{
// Polynomial Curve: dY = dX * ( K0 * (X0 + X1) + K1 )
K = new double[] { 0, (list[1][1] - list[0][1]) / (list[1][0] - list[0][0]) };
curve = Ktype.Polynomial;
return K;
}
double[] dY = { list[list.Count - 2][1] - list[list.Count - 3][1], list[list.Count - 1][1] - list[list.Count - 2][1] };
double[] dX = { list[list.Count - 2][0] - list[list.Count - 3][0], list[list.Count - 1][0] - list[list.Count - 2][0] };
double curvature = (dY[1] / dX[1] - dY[0] / dX[0]) / ((dX[0] + dX[1]) / 2);
if (curvature > 0)
{
// Exponential Curve: Y1/Y0 = EXP(dX * K);
K = new double[] { Math.Log(list.Last()[1] / list[list.Count - 2][1]) / dX[1] };
curve = Ktype.Exponential;
}
else if (curvature < 0 && dY[1] >= 0)
{
// Logarithmic Curve: dY = K * LN(X1/X0);
K = new double[] { dY[1] / Math.Log(list.Last()[0] / list[list.Count - 2][0]) };
curve = Ktype.Logarithmic;
}
else
{
// Polynomial Curve: dY = dX * ( K0 * (X0 + X1) + K1 )
K = new double[] { curvature / 2, dY[1] / dX[1] - (list.Last()[0] + list[list.Count - 2][0]) * curvature / 2 };
curve = Ktype.Polynomial;
}
return K;
}
