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A fast and easy to use dense and sparse matrix linear algebra library written in Java.

There is a newer version: 0.43.1

/*
 * Copyright (c) 2021, Peter Abeles. All Rights Reserved.
 *
 * This file is part of Efficient Java Matrix Library (EJML).
 *
 * Licensed 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
 *
 *   http://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.
 */
package org.ejml.data;

/**
 * High level interface for all sparse matrices
 *
 * @author Peter Abeles
 */
public interface MatrixSparse extends ReshapeMatrix {
    /**
     * Prints to standard out the non-zero elements only.
     */
    void printNonZero();

    /**
     * Reshapes the matrix so that it can store a matrix with the specified dimensions and the number of
     * non-zero elements.  The reshaped matrix will be empty.
     *
     * @param numRows number of rows
     * @param numCols number of columns
     * @param arrayLength Array length for storing non-zero elements.
     */
    void reshape( int numRows , int numCols , int arrayLength );

    /**
     * Changes the number of rows and columns in the matrix. The graph structure is flushed and the matrix will
     * be empty/all zeros.  Similar to {@link #reshape(int, int, int)}, but the storage for non-zero elements is
     * not changed
     *
     * @param numRows number of rows
     * @param numCols number of columns
     */
    @Override
    void reshape( int numRows , int numCols );

    /**
     * Reduces the size of internal data structures to their minimal size.  No information is lost but the arrays will
     * change
     */
    void shrinkArrays();

    /**
     * If the specified element is non-zero it is removed from the structure
     * @param row the row
     * @param col the column
     */
    void remove( int row , int col );

    /**
     * Is the specified element explicitly assigned a value
     * @param row the row
     * @param col the column
     * @return true if it has been assigned a value or false if not
     */
    boolean isAssigned( int row , int col );

    /**
     * Sets all elements to zero by removing the sparse graph
     */
    @Override
    void zero();

    /**
     * Returns the number of non-zero elements.
     */
    int getNonZeroLength();
}