/// <summary>
/// Calculates the back1.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="stepSize">Size of the step.</param>
/// <param name="point">The point.</param>
/// <param name="i">The i.</param>
/// <returns>System.Double.</returns>
private double calcBack1(IOptFunction function, double stepSize, double[] point, int i)
{
var backStep = (double[])point.Clone();
backStep[i] -= stepSize;
return((calculate(function, point) - calculate(function, backStep)) / stepSize);
}
/// <summary>
/// Calculates the forward1.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="stepSize">Size of the step.</param>
/// <param name="point">The point.</param>
/// <param name="i">The i.</param>
/// <returns>System.Double.</returns>
private double calcForward1(IOptFunction function, double stepSize, double[] point, int i)
{
var forStep = (double[])point.Clone();
forStep[i] += stepSize;
return((calculate(function, forStep) - calculate(function, point)) / stepSize);
}
/// <summary>
/// Calculates the derivative with respect to variable xi
/// for the specified function.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="point">The point.</param>
/// <param name="i">The index of the variable in x.</param>
/// <returns>System.Double.</returns>
public double deriv_wrt_xi(IOptFunction function, double[] point, int i)
{
switch (functionData[function].findDerivBy)
{
case differentiate.Analytic:
return(((IDifferentiable)function).deriv_wrt_xi(point, i));
case differentiate.Back1:
return(calcBack1(function, functionData[function].finiteDiffStepSize, point, i));
case differentiate.Forward1:
return(calcForward1(function, functionData[function].finiteDiffStepSize, point, i));
case differentiate.Central2:
return(calcCentral2(function, functionData[function].finiteDiffStepSize, point, i));
case differentiate.Back2:
return(calcBack2(function, functionData[function].finiteDiffStepSize, point, i));
case differentiate.Forward2:
return(calcForward2(function, functionData[function].finiteDiffStepSize, point, i));
case differentiate.Central4:
return(calcCentral4(function, functionData[function].finiteDiffStepSize, point, i));
}
return(double.NaN);
}
/// <summary>
/// Calculates the central2.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="stepSize">Size of the step.</param>
/// <param name="point">The point.</param>
/// <param name="i">The i.</param>
/// <returns>System.Double.</returns>
private double calcCentral2(IOptFunction function, double stepSize, double[] point, int i)
{
var forStep = (double[])point.Clone();
var backStep = (double[])point.Clone();
forStep[i] += stepSize;
backStep[i] -= stepSize;
return((calculate(function, forStep) - calculate(function, backStep)) / (2 * stepSize));
}
/// <summary>
/// Calculates the forward2.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="stepSize">Size of the step.</param>
/// <param name="point">The point.</param>
/// <param name="i">The i.</param>
/// <returns>System.Double.</returns>
private double calcForward2(IOptFunction function, double stepSize, double[] point, int i)
{
var forStep1 = (double[])point.Clone();
forStep1[i] += stepSize;
var forStep2 = (double[])point.Clone();
forStep2[i] += 2 * stepSize;
return((-3 * calculate(function, point) + 4 * calculate(function, forStep1) - calculate(function, forStep2))
/ (2 * stepSize));
}
/// <summary>
/// Calculates the back2.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="stepSize">Size of the step.</param>
/// <param name="point">The point.</param>
/// <param name="i">The i.</param>
/// <returns>System.Double.</returns>
private double calcBack2(IOptFunction function, double stepSize, double[] point, int i)
{
var backStep1 = (double[])point.Clone();
backStep1[i] -= stepSize;
var backStep2 = (double[])point.Clone();
backStep2[i] -= 2 * stepSize;
return((calculate(function, backStep2) - 4 * calculate(function, backStep1) + 3 * calculate(function, point))
/ (2 * stepSize));
}
/// <summary>
/// Initializes a new instance of the <see cref="RecentFunctionEvalStore"/> class.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="comparer">The comparer.</param>
/// <param name="finiteDiffStepSize">Size of the finite difference step.</param>
/// <param name="findDerivBy">The find deriv by.</param>
internal RecentFunctionEvalStore(IOptFunction function, IEqualityComparer <double[]> comparer,
double finiteDiffStepSize, differentiate findDerivBy)
{
if (function is IDifferentiable)
{
this.findDerivBy = differentiate.Analytic;
}
else
{
this.finiteDiffStepSize = finiteDiffStepSize;
this.findDerivBy = findDerivBy;
}
oldEvaluations = new Dictionary <double[], double>(comparer);
queue = new Queue <double[]>();
}
/// <summary>
/// Calculates the central4.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="stepSize">Size of the step.</param>
/// <param name="point">The point.</param>
/// <param name="i">The i.</param>
/// <returns>System.Double.</returns>
private double calcCentral4(IOptFunction function, double stepSize, double[] point, int i)
{
var forStep1 = (double[])point.Clone();
forStep1[i] += stepSize;
var forStep2 = (double[])point.Clone();
forStep2[i] += 2 * stepSize;
var backStep1 = (double[])point.Clone();
backStep1[i] -= stepSize;
var backStep2 = (double[])point.Clone();
backStep2[i] -= 2 * stepSize;
return((calculate(function, backStep2) - 8 * calculate(function, backStep1)
+ 8 * calculate(function, forStep1) - calculate(function, forStep2)) / (12 * stepSize));
}
/// <summary>
/// Calculates the specified function.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="point">The point.</param>
/// <returns>System.Double.</returns>
internal double calculate(IOptFunction function, double[] point)
{
double fValue;
var pointClone = (double[])point.Clone();
SearchIO.output("evaluating x =" + point.MakePrintString(), 4);
if (functionData[function].TryGetValue(pointClone, out fValue))
{
SearchIO.output("f =" + fValue + " (from store).", 4);
return(fValue);
}
calc_dependent_Analysis(point);
/**************************************************/
/*** This is the only function that should call ***/
/**********IOptFunction.calculate(x)***************/
fValue = function.calculate(point);
/**************************************************/
functionData[function].Add(pointClone, fValue);
functionData[function].numEvals++;
SearchIO.output("f =" + fValue + " (f'n eval #" + numEvals + ")", 4);
return(fValue);
}
internal double calculate(IOptFunction function, double[] point)
{
return(function.calculate(point));
}
/// <summary>
/// Calculates the derivative with respect to variable xi
/// for the specified function.
/// </summary>
/// <param name="function">The function.</param>
/// <param name="point">The point.</param>
/// <param name="i">The index of the variable in x.</param>
/// <returns></returns>
internal double deriv_wrt_xi(IOptFunction function, double[] point, int i)
{
return(function.deriv_wrt_xi(point, i));
}