/*
    * 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;
  
  import java.io.Serializable;
  
  import org.apache.commons.math.exception.DimensionMismatchException;
  import org.apache.commons.math.exception.NullArgumentException;
  import org.apache.commons.math.exception.NoDataException;
  import org.apache.commons.math.exception.MathIllegalStateException;
  import org.apache.commons.math.exception.util.LocalizedFormats;
  import org.apache.commons.math.util.MathUtils;
  
  /**
   * Implementation of {@link RealMatrix} using a {@code double[][]} array to
   * store entries.
   *
   * @version $Id: Array2DRowRealMatrix.java 1178186 2011-10-02 13:00:41Z erans $
   */
  public class Array2DRowRealMatrix extends AbstractRealMatrix implements Serializable {
      /** Serializable version identifier. */
      private static final long serialVersionUID = -1067294169172445528L;
      /** Entries of the matrix. */
      protected double data[][];
  
      /**
       * Creates a matrix with no data
       */
      public Array2DRowRealMatrix() {}
  
      /**
       * Create a new RealMatrix with the supplied row and column dimensions.
       *
       * @param rowDimension Number of rows in the new matrix.
       * @param columnDimension Number of columns in the new matrix.
       * @throws org.apache.commons.math.exception.NotStrictlyPositiveException
       * if the row or column dimension is not positive.
       */
      public Array2DRowRealMatrix(final int rowDimension, final int columnDimension) {
          super(rowDimension, columnDimension);
          data = new double[rowDimension][columnDimension];
      }
  
      /**
       * Create a new {@code RealMatrix} using the input array as the underlying
       * data array.
       * <p>The input array is copied, not referenced. This constructor has
       * the same effect as calling {@link #Array2DRowRealMatrix(double[][], boolean)}
       * with the second argument set to {@code true}.</p>
       *
       * @param d Data for the new matrix.
       * @throws DimensionMismatchException if {@code d} is not rectangular.
       * @throws NoDataException if {@code d} row or colum dimension is zero.
       * @throws NullArgumentException if {@code d} is {@code null}.
       * @see #Array2DRowRealMatrix(double[][], boolean)
       */
      public Array2DRowRealMatrix(final double[][] d)
          throws DimensionMismatchException, NoDataException, NullArgumentException {
          copyIn(d);
      }
  
      /**
       * Create a new RealMatrix using the input array as the underlying
       * data array.
       * If an array is built specially in order to be embedded in a
       * RealMatrix and not used directly, the {@code copyArray} may be
       * set to {@code false}. This will prevent the copying and improve
       * performance as no new array will be built and no data will be copied.
       *
       * @param d Data for new matrix.
       * @param copyArray if {@code true}, the input array will be copied,
       * otherwise it will be referenced.
       * @throws DimensionMismatchException if {@code d} is not rectangular
       * (not all rows have the same length) or empty.
       * @throws NullArgumentException if {@code d} is {@code null}.
       * @throws NoDataException if there are not at least one row and one column.
       * @see #Array2DRowRealMatrix(double[][])
       */
      public Array2DRowRealMatrix(final double[][] d, final boolean copyArray) {
          if (copyArray) {
              copyIn(d);
          } else {
              if (d == null) {
                  throw new NullArgumentException();
             }
             final int nRows = d.length;
             if (nRows == 0) {
                 throw new NoDataException(LocalizedFormats.AT_LEAST_ONE_ROW);
             }
             final int nCols = d[0].length;
             if (nCols == 0) {
                 throw new NoDataException(LocalizedFormats.AT_LEAST_ONE_COLUMN);
             }
             for (int r = 1; r < nRows; r++) {
                 if (d[r].length != nCols) {
                     throw new DimensionMismatchException(d[r].length, nCols);
                 }
             }
             data = d;
         }
     }
 
     /**
      * Create a new (column) RealMatrix using {@code v} as the
      * data for the unique column of the created matrix.
      * The input array is copied.
      *
      * @param v Column vector holding data for new matrix.
      */
     public Array2DRowRealMatrix(final double[] v) {
         final int nRows = v.length;
         data = new double[nRows][1];
         for (int row = 0; row < nRows; row++) {
             data[row][0] = v[row];
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public RealMatrix createMatrix(final int rowDimension,
                                    final int columnDimension) {
         return new Array2DRowRealMatrix(rowDimension, columnDimension);
     }
 
     /** {@inheritDoc} */
     @Override
     public RealMatrix copy() {
         return new Array2DRowRealMatrix(copyOut(), false);
     }
 
     /**
      * Compute the sum of this matrix with {@code m}.
      *
      * @param m Matrix to be added.
      * @return {@code this} + m.
      * @throws MatrixDimensionMismatchException
      * if {@code m} is not the same size as this matrix.
      */
     public Array2DRowRealMatrix add(final Array2DRowRealMatrix m) {
         // Safety check.
         MatrixUtils.checkAdditionCompatible(this, m);
 
         final int rowCount    = getRowDimension();
         final int columnCount = getColumnDimension();
         final double[][] outData = new double[rowCount][columnCount];
         for (int row = 0; row < rowCount; row++) {
             final double[] dataRow    = data[row];
             final double[] mRow       = m.data[row];
             final double[] outDataRow = outData[row];
             for (int col = 0; col < columnCount; col++) {
                 outDataRow[col] = dataRow[col] + mRow[col];
             }
         }
 
         return new Array2DRowRealMatrix(outData, false);
     }
 
     /**
      * Subtract {@code m} from this matrix.
      *
      * @param m Matrix to be subtracted.
      * @return {@code this} - m.
      * @throws MatrixDimensionMismatchException
      * if {@code m} is not the same size as this matrix.
      */
     public Array2DRowRealMatrix subtract(final Array2DRowRealMatrix m) {
         // Safety check.
         MatrixUtils.checkSubtractionCompatible(this, m);
 
         final int rowCount    = getRowDimension();
         final int columnCount = getColumnDimension();
         final double[][] outData = new double[rowCount][columnCount];
         for (int row = 0; row < rowCount; row++) {
             final double[] dataRow    = data[row];
             final double[] mRow       = m.data[row];
             final double[] outDataRow = outData[row];
             for (int col = 0; col < columnCount; col++) {
                 outDataRow[col] = dataRow[col] - mRow[col];
             }
         }
 
         return new Array2DRowRealMatrix(outData, false);
     }
 
     /**
      * Postmultiplying this matrix by {@code m}.
      *
      * @param m Matrix to postmultiply by.
      * @return {@code this} * m.
      * @throws DimensionMismatchException if the number of columns of this
      * matrix is not equal to the number of rows of {@code m}.
      */
     public Array2DRowRealMatrix multiply(final Array2DRowRealMatrix m) {
         // Safety check.
         MatrixUtils.checkMultiplicationCompatible(this, m);
 
         final int nRows = this.getRowDimension();
         final int nCols = m.getColumnDimension();
         final int nSum = this.getColumnDimension();
 
         final double[][] outData = new double[nRows][nCols];
         // Will hold a column of "m".
         final double[] mCol = new double[nSum];
         final double[][] mData = m.data;
 
         // Multiply.
         for (int col = 0; col < nCols; col++) {
             // Copy all elements of column "col" of "m" so that
             // will be in contiguous memory.
             for (int mRow = 0; mRow < nSum; mRow++) {
                 mCol[mRow] = mData[mRow][col];
             }
 
             for (int row = 0; row < nRows; row++) {
                 final double[] dataRow = data[row];
                 double sum = 0;
                 for (int i = 0; i < nSum; i++) {
                     sum += dataRow[i] * mCol[i];
                 }
                 outData[row][col] = sum;
             }
         }
 
         return new Array2DRowRealMatrix(outData, false);
     }
 
     /** {@inheritDoc} */
     @Override
     public double[][] getData() {
         return copyOut();
     }
 
     /**
      * Get a reference to the underlying data array.
      *
      * @return 2-dimensional array of entries.
      */
     public double[][] getDataRef() {
         return data;
     }
 
     /** {@inheritDoc} */
     @Override
     public void setSubMatrix(final double[][] subMatrix,
                              final int row, final int column) {
         if (data == null) {
             if (row > 0) {
                 throw new MathIllegalStateException(LocalizedFormats.FIRST_ROWS_NOT_INITIALIZED_YET, row);
             }
             if (column > 0) {
                 throw new MathIllegalStateException(LocalizedFormats.FIRST_COLUMNS_NOT_INITIALIZED_YET, column);
             }
             MathUtils.checkNotNull(subMatrix);
             final int nRows = subMatrix.length;
             if (nRows == 0) {
                 throw new NoDataException(LocalizedFormats.AT_LEAST_ONE_ROW);
             }
 
             final int nCols = subMatrix[0].length;
             if (nCols == 0) {
                 throw new NoDataException(LocalizedFormats.AT_LEAST_ONE_COLUMN);
             }
             data = new double[subMatrix.length][nCols];
             for (int i = 0; i < data.length; ++i) {
                 if (subMatrix[i].length != nCols) {
                     throw new DimensionMismatchException(subMatrix[i].length, nCols);
                 }
                 System.arraycopy(subMatrix[i], 0, data[i + row], column, nCols);
             }
         } else {
             super.setSubMatrix(subMatrix, row, column);
         }
 
     }
 
     /** {@inheritDoc} */
     @Override
     public double getEntry(final int row, final int column) {
         MatrixUtils.checkMatrixIndex(this, row, column);
         return data[row][column];
     }
 
     /** {@inheritDoc} */
     @Override
     public void setEntry(final int row, final int column, final double value) {
         MatrixUtils.checkMatrixIndex(this, row, column);
         data[row][column] = value;
     }
 
     /** {@inheritDoc} */
     @Override
     public void addToEntry(final int row, final int column, final double increment) {
         MatrixUtils.checkMatrixIndex(this, row, column);
         data[row][column] += increment;
     }
 
     /** {@inheritDoc} */
     @Override
     public void multiplyEntry(final int row, final int column, final double factor) {
         MatrixUtils.checkMatrixIndex(this, row, column);
         data[row][column] *= factor;
     }
 
     /** {@inheritDoc} */
     @Override
         public int getRowDimension() {
         return (data == null) ? 0 : data.length;
     }
 
     /** {@inheritDoc} */
     @Override
     public int getColumnDimension() {
         return ((data == null) || (data[0] == null)) ? 0 : data[0].length;
     }
 
     /** {@inheritDoc} */
     @Override
     public double[] operate(final double[] v) {
         final int nRows = this.getRowDimension();
         final int nCols = this.getColumnDimension();
         if (v.length != nCols) {
             throw new DimensionMismatchException(v.length, nCols);
         }
         final double[] out = new double[nRows];
         for (int row = 0; row < nRows; row++) {
             final double[] dataRow = data[row];
             double sum = 0;
             for (int i = 0; i < nCols; i++) {
                 sum += dataRow[i] * v[i];
             }
             out[row] = sum;
         }
         return out;
     }
 
     /** {@inheritDoc} */
     @Override
     public double[] preMultiply(final double[] v) {
         final int nRows = getRowDimension();
         final int nCols = getColumnDimension();
         if (v.length != nRows) {
             throw new DimensionMismatchException(v.length, nRows);
         }
 
         final double[] out = new double[nCols];
         for (int col = 0; col < nCols; ++col) {
             double sum = 0;
             for (int i = 0; i < nRows; ++i) {
                 sum += data[i][col] * v[i];
             }
             out[col] = sum;
         }
 
         return out;
 
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInRowOrder(final RealMatrixChangingVisitor visitor) {
         final int rows    = getRowDimension();
         final int columns = getColumnDimension();
         visitor.start(rows, columns, 0, rows - 1, 0, columns - 1);
         for (int i = 0; i < rows; ++i) {
             final double[] rowI = data[i];
             for (int j = 0; j < columns; ++j) {
                 rowI[j] = visitor.visit(i, j, rowI[j]);
             }
         }
         return visitor.end();
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInRowOrder(final RealMatrixPreservingVisitor visitor) {
         final int rows    = getRowDimension();
         final int columns = getColumnDimension();
         visitor.start(rows, columns, 0, rows - 1, 0, columns - 1);
         for (int i = 0; i < rows; ++i) {
             final double[] rowI = data[i];
             for (int j = 0; j < columns; ++j) {
                 visitor.visit(i, j, rowI[j]);
             }
         }
         return visitor.end();
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInRowOrder(final RealMatrixChangingVisitor visitor,
                                  final int startRow, final int endRow,
                                  final int startColumn, final int endColumn) {
         MatrixUtils.checkSubMatrixIndex(this, startRow, endRow, startColumn, endColumn);
         visitor.start(getRowDimension(), getColumnDimension(),
                       startRow, endRow, startColumn, endColumn);
         for (int i = startRow; i <= endRow; ++i) {
             final double[] rowI = data[i];
             for (int j = startColumn; j <= endColumn; ++j) {
                 rowI[j] = visitor.visit(i, j, rowI[j]);
             }
         }
         return visitor.end();
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInRowOrder(final RealMatrixPreservingVisitor visitor,
                                  final int startRow, final int endRow,
                                  final int startColumn, final int endColumn) {
         MatrixUtils.checkSubMatrixIndex(this, startRow, endRow, startColumn, endColumn);
         visitor.start(getRowDimension(), getColumnDimension(),
                       startRow, endRow, startColumn, endColumn);
         for (int i = startRow; i <= endRow; ++i) {
             final double[] rowI = data[i];
             for (int j = startColumn; j <= endColumn; ++j) {
                 visitor.visit(i, j, rowI[j]);
             }
         }
         return visitor.end();
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInColumnOrder(final RealMatrixChangingVisitor visitor) {
         final int rows    = getRowDimension();
         final int columns = getColumnDimension();
         visitor.start(rows, columns, 0, rows - 1, 0, columns - 1);
         for (int j = 0; j < columns; ++j) {
             for (int i = 0; i < rows; ++i) {
                 final double[] rowI = data[i];
                 rowI[j] = visitor.visit(i, j, rowI[j]);
             }
         }
         return visitor.end();
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInColumnOrder(final RealMatrixPreservingVisitor visitor) {
         final int rows    = getRowDimension();
         final int columns = getColumnDimension();
         visitor.start(rows, columns, 0, rows - 1, 0, columns - 1);
         for (int j = 0; j < columns; ++j) {
             for (int i = 0; i < rows; ++i) {
                 visitor.visit(i, j, data[i][j]);
             }
         }
         return visitor.end();
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInColumnOrder(final RealMatrixChangingVisitor visitor,
                                     final int startRow, final int endRow,
                                     final int startColumn, final int endColumn) {
         MatrixUtils.checkSubMatrixIndex(this, startRow, endRow, startColumn, endColumn);
         visitor.start(getRowDimension(), getColumnDimension(),
                       startRow, endRow, startColumn, endColumn);
         for (int j = startColumn; j <= endColumn; ++j) {
             for (int i = startRow; i <= endRow; ++i) {
                 final double[] rowI = data[i];
                 rowI[j] = visitor.visit(i, j, rowI[j]);
             }
         }
         return visitor.end();
     }
 
     /** {@inheritDoc} */
     @Override
     public double walkInColumnOrder(final RealMatrixPreservingVisitor visitor,
                                     final int startRow, final int endRow,
                                     final int startColumn, final int endColumn) {
         MatrixUtils.checkSubMatrixIndex(this, startRow, endRow, startColumn, endColumn);
         visitor.start(getRowDimension(), getColumnDimension(),
                       startRow, endRow, startColumn, endColumn);
         for (int j = startColumn; j <= endColumn; ++j) {
             for (int i = startRow; i <= endRow; ++i) {
                 visitor.visit(i, j, data[i][j]);
             }
         }
         return visitor.end();
     }
 
     /**
      * Get a fresh copy of the underlying data array.
      *
      * @return a copy of the underlying data array.
      */
     private double[][] copyOut() {
         final int nRows = this.getRowDimension();
         final double[][] out = new double[nRows][this.getColumnDimension()];
         // can't copy 2-d array in one shot, otherwise get row references
         for (int i = 0; i < nRows; i++) {
             System.arraycopy(data[i], 0, out[i], 0, data[i].length);
         }
         return out;
     }
 
     /**
      * Replace data with a fresh copy of the input array.
      *
      * @param in Data to copy.
      * @throws NoDataException if the input array is empty.
      * @throws DimensionMismatchException if the input array is not rectangular.
      * @throws NullArgumentException if
      * the input array is {@code null}.
      */
     private void copyIn(final double[][] in)
         throws DimensionMismatchException, NoDataException, NullArgumentException {
         setSubMatrix(in, 0, 0);
     }
 }