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