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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.geometry.core;
    18
    19  /** Interface representing a point in a mathematical space.
    20   *
    21   * <p>Implementations of this interface are sufficient to define a
    22   * space since they define both the structure of the points making up
    23   * the space and the operations permitted on them. The only mathematical
    24   * requirement at this level is that the represented space have a defined
    25   * distance metric, meaning an operation that can compute the distance
    26   * between two points (ie, the space must be a metric space).
    27   * </p>
    28   *
    29   * <p>This interface uses self-referencing generic parameters to ensure
    30   * that implementations are only used with instances of their own type.
    31   * This removes the need for casting inside of methods in order to access
    32   * implementation-specific data, such as coordinate values.
    33   * </p>
    34   *
    35   * @see <a href="https://en.wikipedia.org/wiki/Metric_space">Metric space</a>
    36   *
    37   * @param <P> Point implementation type
    38   */
    39  public interface Point<P extends Point<P>> extends Spatial {
    40
    41      /** Compute the distance between this point and another point.
    42       * @param p second point
    43       * @return the distance between this point and p
    44       */
    45      double distance(P p);
    46  }