cern.colt.matrix.impl
Class DenseDoubleMatrix2D

java.lang.Object
  extended by cern.colt.PersistentObject
      extended by cern.colt.matrix.impl.AbstractMatrix
          extended by cern.colt.matrix.impl.AbstractMatrix2D
              extended by cern.colt.matrix.DoubleMatrix2D
                  extended by cern.colt.matrix.impl.DenseDoubleMatrix2D
All Implemented Interfaces:
java.io.Serializable, java.lang.Cloneable

public class DenseDoubleMatrix2D
extends DoubleMatrix2D

Dense 2-d matrix holding double elements. First see the package summary and javadoc tree view to get the broad picture.

Implementation:

Internally holds one single contigous one-dimensional array, addressed in row major. Note that this implementation is not synchronized.

Memory requirements:

memory [bytes] = 8*rows()*columns(). Thus, a 1000*1000 matrix uses 8 MB.

Time complexity:

O(1) (i.e. constant time) for the basic operations get, getQuick, set, setQuick and size,

Cells are internally addressed in row-major. Applications demanding utmost speed can exploit this fact. Setting/getting values in a loop row-by-row is quicker than column-by-column. Thus

   for (int row=0; row < rows; row++) {
          for (int column=0; column < columns; column++) {
                 matrix.setQuick(row,column,someValue);
          }
   }
is quicker than
   for (int column=0; column < columns; column++) {
          for (int row=0; row < rows; row++) {
                 matrix.setQuick(row,column,someValue);
          }
   }

Author:
wolfgang.hoschek@cern.ch
See Also:
Serialized Form

Field Summary
protected  double[] elements
          The elements of this matrix.
 
Fields inherited from class cern.colt.matrix.impl.AbstractMatrix2D
columns, columnStride, columnZero, rows, rowStride, rowZero
 
Fields inherited from class cern.colt.matrix.impl.AbstractMatrix
isNoView
 
Constructor Summary
  DenseDoubleMatrix2D(double[][] values)
          Constructs a matrix with a copy of the given values.
  DenseDoubleMatrix2D(int rows, int columns)
          Constructs a matrix with a given number of rows and columns.
protected DenseDoubleMatrix2D(int rows, int columns, double[] elements, int rowZero, int columnZero, int rowStride, int columnStride)
          Constructs a view with the given parameters.
 
Method Summary
 DoubleMatrix2D assign(double value)
          Sets all cells to the state specified by value.
 DoubleMatrix2D assign(double[][] values)
          Sets all cells to the state specified by values.
 DoubleMatrix2D assign(DoubleFunction function)
          Assigns the result of a function to each cell; x[row,col] = function(x[row,col]).
 DoubleMatrix2D assign(DoubleMatrix2D source)
          Replaces all cell values of the receiver with the values of another matrix.
 DoubleMatrix2D assign(DoubleMatrix2D y, DoubleDoubleFunction function)
          Assigns the result of a function to each cell; x[row,col] = function(x[row,col],y[row,col]).
 double getQuick(int row, int column)
          Returns the matrix cell value at coordinate [row,column].
protected  boolean haveSharedCellsRaw(DoubleMatrix2D other)
          Returns true if both matrices share common cells.
protected  int index(int row, int column)
          Returns the position of the given coordinate within the (virtual or non-virtual) internal 1-dimensional array.
 DoubleMatrix2D like(int rows, int columns)
          Construct and returns a new empty matrix of the same dynamic type as the receiver, having the specified number of rows and columns.
 DoubleMatrix1D like1D(int size)
          Construct and returns a new 1-d matrix of the corresponding dynamic type, entirelly independent of the receiver.
protected  DoubleMatrix1D like1D(int size, int zero, int stride)
          Construct and returns a new 1-d matrix of the corresponding dynamic type, sharing the same cells.
 void setQuick(int row, int column, double value)
          Sets the matrix cell at coordinate [row,column] to the specified value.
protected  DoubleMatrix2D viewSelectionLike(int[] rowOffsets, int[] columnOffsets)
          Construct and returns a new selection view.
 void zAssign8Neighbors(DoubleMatrix2D B, Double9Function function)
          8 neighbor stencil transformation.
 DoubleMatrix1D zMult(DoubleMatrix1D y, DoubleMatrix1D z, double alpha, double beta, boolean transposeA)
          Linear algebraic matrix-vector multiplication; z = alpha * A * y + beta*z.
 DoubleMatrix2D zMult(DoubleMatrix2D B, DoubleMatrix2D C, double alpha, double beta, boolean transposeA, boolean transposeB)
          Linear algebraic matrix-matrix multiplication; C = alpha * A x B + beta*C.
 double zSum()
          Returns the sum of all cells; Sum( x[i,j] ).
 
Methods inherited from class cern.colt.matrix.DoubleMatrix2D
aggregate, aggregate, cardinality, copy, equals, equals, forEachNonZero, get, getContent, getNonZeros, haveSharedCells, like, set, toArray, toString, view, viewColumn, viewColumnFlip, viewDice, viewPart, viewRow, viewRowFlip, viewSelection, viewSelection, viewSorted, viewStrides, zMult, zMult
 
Methods inherited from class cern.colt.matrix.impl.AbstractMatrix2D
_columnOffset, _columnRank, _rowOffset, _rowRank, checkBox, checkColumn, checkColumnIndexes, checkRow, checkRowIndexes, checkShape, checkShape, columns, rows, setUp, setUp, size, toStringShort, vColumnFlip, vDice, vPart, vRowFlip, vStrides
 
Methods inherited from class cern.colt.matrix.impl.AbstractMatrix
ensureCapacity, isView, trimToSize
 
Methods inherited from class cern.colt.PersistentObject
clone
 
Methods inherited from class java.lang.Object
finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

elements

protected double[] elements
The elements of this matrix. elements are stored in row major, i.e. index==row*columns + column columnOf(index)==index%columns rowOf(index)==index/columns i.e. {row0 column0..m}, {row1 column0..m}, ..., {rown column0..m}

Constructor Detail

DenseDoubleMatrix2D

public DenseDoubleMatrix2D(double[][] values)
Constructs a matrix with a copy of the given values. values is required to have the form values[row][column] and have exactly the same number of columns in every row.

The values are copied. So subsequent changes in values are not reflected in the matrix, and vice-versa.

Parameters:
values - The values to be filled into the new matrix.
Throws:
java.lang.IllegalArgumentException - if for any 1 <= row < values.length: values[row].length != values[row-1].length.

DenseDoubleMatrix2D

public DenseDoubleMatrix2D(int rows,
                           int columns)
Constructs a matrix with a given number of rows and columns. All entries are initially 0.

Parameters:
rows - the number of rows the matrix shall have.
columns - the number of columns the matrix shall have.
Throws:
java.lang.IllegalArgumentException - if rows<0 || columns<0 || (double)columns*rows > Integer.MAX_VALUE.

DenseDoubleMatrix2D

protected DenseDoubleMatrix2D(int rows,
                              int columns,
                              double[] elements,
                              int rowZero,
                              int columnZero,
                              int rowStride,
                              int columnStride)
Constructs a view with the given parameters.

Parameters:
rows - the number of rows the matrix shall have.
columns - the number of columns the matrix shall have.
elements - the cells.
rowZero - the position of the first element.
columnZero - the position of the first element.
rowStride - the number of elements between two rows, i.e. index(i+1,j)-index(i,j).
columnStride - the number of elements between two columns, i.e. index(i,j+1)-index(i,j).
Throws:
java.lang.IllegalArgumentException - if rows<0 || columns<0 || (double)columns*rows > Integer.MAX_VALUE or flip's are illegal.
Method Detail

assign

public DoubleMatrix2D assign(double[][] values)
Sets all cells to the state specified by values. values is required to have the form values[row][column] and have exactly the same number of rows and columns as the receiver.

The values are copied. So subsequent changes in values are not reflected in the matrix, and vice-versa.

Overrides:
assign in class DoubleMatrix2D
Parameters:
values - the values to be filled into the cells.
Returns:
this (for convenience only).
Throws:
java.lang.IllegalArgumentException - if values.length != rows() || for any 0 <= row < rows(): values[row].length != columns().

assign

public DoubleMatrix2D assign(double value)
Sets all cells to the state specified by value.

Overrides:
assign in class DoubleMatrix2D
Parameters:
value - the value to be filled into the cells.
Returns:
this (for convenience only).

assign

public DoubleMatrix2D assign(DoubleFunction function)
Assigns the result of a function to each cell; x[row,col] = function(x[row,col]).

Example:

matrix = 2 x 2 matrix
0.5 1.5      
2.5 3.5

// change each cell to its sine
matrix.assign(cern.jet.math.Functions.sin);
-->
2 x 2 matrix
0.479426  0.997495 
0.598472 -0.350783
For further examples, see the package doc.

Overrides:
assign in class DoubleMatrix2D
Parameters:
function - a function object taking as argument the current cell's value.
Returns:
this (for convenience only).
See Also:
Functions

assign

public DoubleMatrix2D assign(DoubleMatrix2D source)
Replaces all cell values of the receiver with the values of another matrix. Both matrices must have the same number of rows and columns. If both matrices share the same cells (as is the case if they are views derived from the same matrix) and intersect in an ambiguous way, then replaces as if using an intermediate auxiliary deep copy of other.

Overrides:
assign in class DoubleMatrix2D
Parameters:
source - the source matrix to copy from (may be identical to the receiver).
Returns:
this (for convenience only).
Throws:
java.lang.IllegalArgumentException - if columns() != source.columns() || rows() != source.rows()

assign

public DoubleMatrix2D assign(DoubleMatrix2D y,
                             DoubleDoubleFunction function)
Assigns the result of a function to each cell; x[row,col] = function(x[row,col],y[row,col]).

Example:

// assign x[row,col] = x[row,col]y[row,col]
m1 = 2 x 2 matrix 
0 1 
2 3

m2 = 2 x 2 matrix 
0 2 
4 6

m1.assign(m2, cern.jet.math.Functions.pow);
-->
m1 == 2 x 2 matrix
 1   1 
16 729
For further examples, see the package doc.

Overrides:
assign in class DoubleMatrix2D
Parameters:
y - the secondary matrix to operate on.
function - a function object taking as first argument the current cell's value of this, and as second argument the current cell's value of y,
Returns:
this (for convenience only).
Throws:
java.lang.IllegalArgumentException - if columns() != other.columns() || rows() != other.rows()
See Also:
Functions

getQuick

public double getQuick(int row,
                       int column)
Returns the matrix cell value at coordinate [row,column].

Provided with invalid parameters this method may return invalid objects without throwing any exception. You should only use this method when you are absolutely sure that the coordinate is within bounds. Precondition (unchecked): 0 <= column < columns() && 0 <= row < rows().

Specified by:
getQuick in class DoubleMatrix2D
Parameters:
row - the index of the row-coordinate.
column - the index of the column-coordinate.
Returns:
the value at the specified coordinate.

haveSharedCellsRaw

protected boolean haveSharedCellsRaw(DoubleMatrix2D other)
Returns true if both matrices share common cells. More formally, returns true if other != null and at least one of the following conditions is met

Overrides:
haveSharedCellsRaw in class DoubleMatrix2D

index

protected int index(int row,
                    int column)
Returns the position of the given coordinate within the (virtual or non-virtual) internal 1-dimensional array.

Overrides:
index in class AbstractMatrix2D
Parameters:
row - the index of the row-coordinate.
column - the index of the column-coordinate.

like

public DoubleMatrix2D like(int rows,
                           int columns)
Construct and returns a new empty matrix of the same dynamic type as the receiver, having the specified number of rows and columns. For example, if the receiver is an instance of type DenseDoubleMatrix2D the new matrix must also be of type DenseDoubleMatrix2D, if the receiver is an instance of type SparseDoubleMatrix2D the new matrix must also be of type SparseDoubleMatrix2D, etc. In general, the new matrix should have internal parametrization as similar as possible.

Specified by:
like in class DoubleMatrix2D
Parameters:
rows - the number of rows the matrix shall have.
columns - the number of columns the matrix shall have.
Returns:
a new empty matrix of the same dynamic type.

like1D

public DoubleMatrix1D like1D(int size)
Construct and returns a new 1-d matrix of the corresponding dynamic type, entirelly independent of the receiver. For example, if the receiver is an instance of type DenseDoubleMatrix2D the new matrix must be of type DenseDoubleMatrix1D, if the receiver is an instance of type SparseDoubleMatrix2D the new matrix must be of type SparseDoubleMatrix1D, etc.

Specified by:
like1D in class DoubleMatrix2D
Parameters:
size - the number of cells the matrix shall have.
Returns:
a new matrix of the corresponding dynamic type.

like1D

protected DoubleMatrix1D like1D(int size,
                                int zero,
                                int stride)
Construct and returns a new 1-d matrix of the corresponding dynamic type, sharing the same cells. For example, if the receiver is an instance of type DenseDoubleMatrix2D the new matrix must be of type DenseDoubleMatrix1D, if the receiver is an instance of type SparseDoubleMatrix2D the new matrix must be of type SparseDoubleMatrix1D, etc.

Specified by:
like1D in class DoubleMatrix2D
Parameters:
size - the number of cells the matrix shall have.
zero - the index of the first element.
stride - the number of indexes between any two elements, i.e. index(i+1)-index(i).
Returns:
a new matrix of the corresponding dynamic type.

setQuick

public void setQuick(int row,
                     int column,
                     double value)
Sets the matrix cell at coordinate [row,column] to the specified value.

Provided with invalid parameters this method may access illegal indexes without throwing any exception. You should only use this method when you are absolutely sure that the coordinate is within bounds. Precondition (unchecked): 0 <= column < columns() && 0 <= row < rows().

Specified by:
setQuick in class DoubleMatrix2D
Parameters:
row - the index of the row-coordinate.
column - the index of the column-coordinate.
value - the value to be filled into the specified cell.

viewSelectionLike

protected DoubleMatrix2D viewSelectionLike(int[] rowOffsets,
                                           int[] columnOffsets)
Construct and returns a new selection view.

Specified by:
viewSelectionLike in class DoubleMatrix2D
Parameters:
rowOffsets - the offsets of the visible elements.
columnOffsets - the offsets of the visible elements.
Returns:
a new view.

zAssign8Neighbors

public void zAssign8Neighbors(DoubleMatrix2D B,
                              Double9Function function)
8 neighbor stencil transformation. For efficient finite difference operations. Applies a function to a moving 3 x 3 window. Does nothing if rows() < 3 || columns() < 3.
B[i,j] = function.apply(
   A[i-1,j-1], A[i-1,j], A[i-1,j+1],
   A[i,  j-1], A[i,  j], A[i,  j+1],
   A[i+1,j-1], A[i+1,j], A[i+1,j+1]
   )

x x x -     - x x x     - - - - 
x o x -     - x o x     - - - - 
x x x -     - x x x ... - x x x 
- - - -     - - - -     - x o x 
- - - -     - - - -     - x x x 
Make sure that cells of this and B do not overlap. In case of overlapping views, behaviour is unspecified.

Example:

final double alpha = 0.25;
final double beta = 0.75;

// 8 neighbors
cern.colt.function.Double9Function f = new cern.colt.function.Double9Function() {
   public final double apply(
      double a00, double a01, double a02,
      double a10, double a11, double a12,
      double a20, double a21, double a22) {
         return beta*a11 + alpha*(a00+a01+a02 + a10+a12 + a20+a21+a22);
      }
};
A.zAssign8Neighbors(B,f);

// 4 neighbors
cern.colt.function.Double9Function g = new cern.colt.function.Double9Function() {
   public final double apply(
      double a00, double a01, double a02,
      double a10, double a11, double a12,
      double a20, double a21, double a22) {
      return beta*a11 + alpha*(a01+a10+a12+a21);
   }
C.zAssign8Neighbors(B,g); // fast, even though it doesn't look like it
};

Overrides:
zAssign8Neighbors in class DoubleMatrix2D
Parameters:
B - the matrix to hold the results.
function - the function to be applied to the 9 cells.
Throws:
java.lang.NullPointerException - if function==null.
java.lang.IllegalArgumentException - if rows() != B.rows() || columns() != B.columns().

zMult

public DoubleMatrix1D zMult(DoubleMatrix1D y,
                            DoubleMatrix1D z,
                            double alpha,
                            double beta,
                            boolean transposeA)
Description copied from class: DoubleMatrix2D
Linear algebraic matrix-vector multiplication; z = alpha * A * y + beta*z. z[i] = alpha*Sum(A[i,j] * y[j]) + beta*z[i], i=0..A.rows()-1, j=0..y.size()-1. Where A == this.
Note: Matrix shape conformance is checked after potential transpositions.

Overrides:
zMult in class DoubleMatrix2D
Parameters:
y - the source vector.
z - the vector where results are to be stored. Set this parameter to null to indicate that a new result vector shall be constructed.
Returns:
z (for convenience only).

zMult

public DoubleMatrix2D zMult(DoubleMatrix2D B,
                            DoubleMatrix2D C,
                            double alpha,
                            double beta,
                            boolean transposeA,
                            boolean transposeB)
Description copied from class: DoubleMatrix2D
Linear algebraic matrix-matrix multiplication; C = alpha * A x B + beta*C. C[i,j] = alpha*Sum(A[i,k] * B[k,j]) + beta*C[i,j], k=0..n-1.
Matrix shapes: A(m x n), B(n x p), C(m x p).
Note: Matrix shape conformance is checked after potential transpositions.

Overrides:
zMult in class DoubleMatrix2D
Parameters:
B - the second source matrix.
C - the matrix where results are to be stored. Set this parameter to null to indicate that a new result matrix shall be constructed.
Returns:
C (for convenience only).

zSum

public double zSum()
Returns the sum of all cells; Sum( x[i,j] ).

Overrides:
zSum in class DoubleMatrix2D
Returns:
the sum.