SparseRealVector.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * This is not the original file distributed by the Apache Software Foundation
 * It has been modified by the Hipparchus project
 */
package org.hipparchus.linear;

/**
 * Marker class for RealVectors that require sparse backing storage
 * <p>
 *  Caveat: Implementation are allowed to assume that, for any {@code x},
 *  the equality {@code x * 0d == 0d} holds. But it is is not true for
 *  {@code NaN}. Moreover, zero entries will lose their sign.
 *  Some operations (that involve {@code NaN} and/or infinities) may
 *  thus give incorrect results, like multiplications, divisions or
 *  functions mapping.
 * </p>
 */
public abstract class SparseRealVector extends RealVector {

    /** Empty constructor.
     * <p>
     * This constructor is not strictly necessary, but it prevents spurious
     * javadoc warnings with JDK 18 and later.
     * </p>
     * @since 3.0
     */
    protected SparseRealVector() { // NOPMD - unnecessary constructor added intentionally to make javadoc happy
        // nothing to do
    }

} // NOPMD - this is an intentional marker class