/// <summary>
/// Build an instance representing a variable.
/// <para>Instances built using this constructor are considered
/// to be the free variables with respect to which differentials
/// are computed. As such, their differential with respect to
/// themselves is +1.</para>
/// </summary>
/// <param name="parameters">number of free parameters</param>
/// <param name="order">derivation order</param>
/// <param name="index">index of the variable (from 0 to <c>parameters - 1</c>)</param>
/// <param name="value">value of the variable</param>
/// <exception cref="NumberIsTooLargeException"> if <c>index >= parameters</c>.</exception>
/// <remarks>
/// See <see cref="DerivativeStructure(int, int, double)"/>
/// </remarks>
public DerivativeStructure(int parameters, int order, int index, double value)
: this(parameters, order, value)
{
if (index >= parameters)
{
throw new NumberIsTooLargeException <Int32, Int32>(index, parameters, false);
}
if (order > 0)
{
// the derivative of the variable with respect to itself is 1.
data[DSCompiler.getCompiler(index, order).getSize()] = 1.0;
}
}
/// <summary>
/// Build an instance with all values and derivatives set to 0.
/// </summary>
/// <param name="parameters">number of free parameters</param>
/// <param name="order">derivation order</param>
/// <exception cref="NumberIsTooLargeException"> if order is too large</exception>
public DerivativeStructure(int parameters, int order) : this(DSCompiler.getCompiler(parameters, order))
{
}
