/// <summary>Initializes a new <see cref="ApproximatelyDifferentiableMDFunction"/> given an <see cref="IMultidimensionalFunction"/>
/// whose gradient should be approximated using a forward-difference method, and the difference factor.
/// </summary>
/// <param name="function">The function whose gradient will be approximated.</param>
/// <param name="factor">A very small positive quantity representing fractional amount by which each argument will be increased when
/// computing the gradient. The default (used by <see cref="ApproximatelyDifferentiableVVFunction(IVectorValuedFunction)"/>) is
/// 0.00000001 (i.e. 1e-8). Smaller values might give a better approximation, but are more susceptible to roundoff error.
/// </param>
public ApproximatelyDifferentiableMDFunction(IMultidimensionalFunction function, double factor)
{
if (function == null)
{
throw new ArgumentNullException();
}
if (factor <= 0)
{
throw new ArgumentOutOfRangeException();
}
this.function = function;
this.input2 = new double[function.Arity]; // the array used to hold x+h
this.factor = factor;
}
/// <summary>Initializes a new <see cref="ApproximatelyDifferentiableMDFunction"/> given an <see cref="IMultidimensionalFunction"/>
/// whose gradient should be approximated using a forward-difference method.
/// </summary>
public ApproximatelyDifferentiableMDFunction(IMultidimensionalFunction function) : this(function, 1e-8)
{
}
