realmatrix.java

Apache的common math数学软件包

/*
 * 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
 *
 *      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.apache.commons.math.linear;

/**
 * Interface defining a real-valued matrix with basic algebraic operations.
 * <p>
 * Matrix element indexing is 0-based -- e.g., <code>getEntry(0, 0)</code>
 * returns the element in the first row, first column of the matrix.</p>
 * 
 * @version $Revision: 617953 $ $Date: 2008-02-02 22:54:00 -0700 (Sat, 02 Feb 2008) $
 */
public interface RealMatrix {
    /**
     * Returns a (deep) copy of this.
     *
     * @return matrix copy
     */
    RealMatrix copy();

    /**
     * Compute the sum of this and m.
     *
     * @param m    matrix to be added
     * @return     this + m
     * @throws  IllegalArgumentException if m is not the same size as this
     */
    RealMatrix add(RealMatrix m) throws IllegalArgumentException;

    /**
     * Compute this minus m.
     *
     * @param m    matrix to be subtracted
     * @return     this + m
     * @throws  IllegalArgumentException if m is not the same size as this
     */
    RealMatrix subtract(RealMatrix m) throws IllegalArgumentException;

     /**
     * Returns the result of adding d to each entry of this.
     *
     * @param d    value to be added to each entry
     * @return     d + this
     */
    RealMatrix scalarAdd(double d);

    /**
     * Returns the result multiplying each entry of this by d.
     *
     * @param d    value to multiply all entries by
     * @return     d * this
     */
    RealMatrix scalarMultiply(double d);

    /**
     * Returns the result of postmultiplying this by m.
     *
     * @param m    matrix to postmultiply by
     * @return     this * m
     * @throws     IllegalArgumentException
     *             if columnDimension(this) != rowDimension(m)
     */
    RealMatrix multiply(RealMatrix m) throws IllegalArgumentException;

    /**
     * Returns the result premultiplying this by <code>m</code>.
     * @param m    matrix to premultiply by
     * @return     m * this
     * @throws     IllegalArgumentException
     *             if rowDimension(this) != columnDimension(m)
     */
    public RealMatrix preMultiply(RealMatrix m) throws IllegalArgumentException;

    /**
     * Returns matrix entries as a two-dimensional array.
     *
     * @return    2-dimensional array of entries
     */
    double[][] getData();

    /**
     * Returns the <a href="http://mathworld.wolfram.com/MaximumAbsoluteRowSumNorm.html">
     * maximum absolute row sum norm</a> of the matrix.
     *
     * @return norm
     */
    double getNorm();
    
    /**
     * Gets a submatrix. Rows and columns are indicated
     * counting from 0 to n-1.
     *
     * @param startRow Initial row index
     * @param endRow Final row index
     * @param startColumn Initial column index
     * @param endColumn Final column index
     * @return The subMatrix containing the data of the
     *         specified rows and columns
     * @exception MatrixIndexException  if the indices are not valid
     */
   RealMatrix getSubMatrix(int startRow, int endRow, int startColumn,
            int endColumn) throws MatrixIndexException;
   
   /**
    * Gets a submatrix. Rows and columns are indicated
    * counting from 0 to n-1.
    *
    * @param selectedRows Array of row indices.
    * @param selectedColumns Array of column indices.
    * @return The subMatrix containing the data in the
    *         specified rows and columns
    * @exception MatrixIndexException if row or column selections are not valid
    */
   RealMatrix getSubMatrix(int[] selectedRows, int[] selectedColumns)
   throws MatrixIndexException;
   
   /**
    * Returns the entries in row number <code>row</code>
    * as a row matrix.  Row indices start at 0.
    *
    * @param row the row to be fetched
    * @return row matrix
    * @throws MatrixIndexException if the specified row index is invalid
    */
   RealMatrix getRowMatrix(int row) throws MatrixIndexException;
   
   /**
    * Returns the entries in column number <code>column</code>
    * as a column matrix.  Column indices start at 0.
    *
    * @param column the column to be fetched
    * @return column matrix
    * @throws MatrixIndexException if the specified column index is invalid
    */
   RealMatrix getColumnMatrix(int column) throws MatrixIndexException;
    
    /**
     * Returns the entries in row number <code>row</code> as an array.
     * <p>
     * Row indices start at 0.  A <code>MatrixIndexException</code> is thrown
     * unless <code>0 <= row < rowDimension.</code></p>
     *
     * @param row the row to be fetched
     * @return array of entries in the row
     * @throws MatrixIndexException if the specified row index is not valid
     */
    double[] getRow(int row) throws MatrixIndexException;

    /**
     * Returns the entries in column number <code>col</code> as an array.
     * <p>
     * Column indices start at 0.  A <code>MatrixIndexException</code> is thrown
     * unless <code>0 <= column < columnDimension.</code></p>
     *
     * @param col the column to be fetched
     * @return array of entries in the column
     * @throws MatrixIndexException if the specified column index is not valid
     */
    double[] getColumn(int col) throws MatrixIndexException;

    /**
     * Returns the entry in the specified row and column.
     * <p>
     * Row and column indices start at 0 and must satisfy 
     * <ul>
     * <li><code>0 <= row < rowDimension</code></li>
     * <li><code> 0 <= column < columnDimension</code></li>
     * </ul>
     * otherwise a <code>MatrixIndexException</code> is thrown.</p>
     * 
     * @param row  row location of entry to be fetched
     * @param column  column location of entry to be fetched
     * @return matrix entry in row,column
     * @throws MatrixIndexException if the row or column index is not valid
     */
    double getEntry(int row, int column) throws MatrixIndexException;

    /**
     * Returns the transpose of this matrix.
     *
     * @return transpose matrix
     */
    RealMatrix transpose();

    /**
     * Returns the inverse of this matrix.
     *
     * @return inverse matrix
     * @throws InvalidMatrixException if  this is not invertible
     */
    RealMatrix inverse() throws InvalidMatrixException;

    /**
     * Returns the determinant of this matrix.
     *
     * @return determinant
     */
    double getDeterminant();

    /**
     * Is this a square matrix?
     * @return true if the matrix is square (rowDimension = columnDimension)
     */
    boolean isSquare();

    /**
     * Is this a singular matrix?
     * @return true if the matrix is singular
     */
    boolean isSingular();

    /**
     * Returns the number of rows in the matrix.
     *
     * @return rowDimension
     */
    int getRowDimension();

    /**
     * Returns the number of columns in the matrix.
     *
     * @return columnDimension
     */
    int getColumnDimension();

    /**
     * Returns the <a href="http://mathworld.wolfram.com/MatrixTrace.html">
     * trace</a> of the matrix (the sum of the elements on the main diagonal).
     *
     * @return trace
     */
    double getTrace();

    /**
     * Returns the result of multiplying this by the vector <code>v</code>.
     *
     * @param v the vector to operate on
     * @return this*v
     * @throws IllegalArgumentException if columnDimension != v.size()
     */
    double[] operate(double[] v) throws IllegalArgumentException;

    /**
     * Returns the (row) vector result of premultiplying this by the vector <code>v</code>.
     *
     * @param v the row vector to premultiply by
     * @return v*this
     * @throws IllegalArgumentException if rowDimension != v.size()
     */
    double[] preMultiply(double[] v) throws IllegalArgumentException;

    /**
     * Returns the solution vector for a linear system with coefficient
     * matrix = this and constant vector = <code>b</code>.
     *
     * @param b  constant vector
     * @return vector of solution values to AX = b, where A is *this
     * @throws IllegalArgumentException if this.rowDimension != b.length
     * @throws InvalidMatrixException if this matrix is not square or is singular
     */
    double[] solve(double[] b) throws IllegalArgumentException, InvalidMatrixException;

    /**
     * Returns a matrix of (column) solution vectors for linear systems with
     * coefficient matrix = this and constant vectors = columns of
     * <code>b</code>.
     *
     * @param b  matrix of constant vectors forming RHS of linear systems to
     * to solve
     * @return matrix of solution vectors
     * @throws IllegalArgumentException if this.rowDimension != row dimension
     * @throws InvalidMatrixException if this matrix is not square or is singular
     */
    RealMatrix solve(RealMatrix b) throws IllegalArgumentException, InvalidMatrixException;
}