package edu.stanford.nlp.optimization;/** * An interface for double-valued functions over double arrays.   * * @author <a href="mailto:klein@cs.stanford.edu">Dan Klein</a> * @version 1.0 * @since 1.0 */public interface Function {  /**   * Returns the value of the function at a single point.   *   * @param x a <code>double[]</code> input   * @return the function value at the input   */  double valueAt(double[] x);  /**   * Returns the number of dimensions in the function's domain   *   * @return the number of domain dimensions   */  int domainDimension();}