/// <inheritdoc/>
 public DerivativeStructure getZero()
 {
     return(new DerivativeStructure(compiler.getFreeParameters(), compiler.getOrder(), 0.0));
 }
 /// <summary>
 /// Get the derivation order.
 /// </summary>
 /// <returns>derivation order</returns>
 public int getOrder()
 {
     return(compiler.getOrder());
 }