cern.colt.matrix.impl
Class DenseDoubleMatrix2D

java.lang.Object
  cern.colt.PersistentObject
      cern.colt.matrix.impl.AbstractMatrix
          cern.colt.matrix.impl.AbstractMatrix2D
              cern.colt.matrix.DoubleMatrix2D
                  cern.colt.matrix.impl.DenseDoubleMatrix2D

All Implemented Interfaces:

Cloneable, Serializable

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);
          }
   }

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

Version:

1.0, 09/24/99

See Also:

Serialized Form

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:

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:

IllegalArgumentException - if rows<0 || columns<0 || (double)columns*rows > Integer.MAX_VALUE.

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:

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:

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:

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.

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.

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.

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:

NullPointerException - if function==null.

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.