java.lang.Object
- no.uib.cipr.matrix.Matrices

public final class Matrices
extends java.lang.Object

Static utility methods for matrices and vectors

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static int`	`cardinality(Matrix A)`	Returns the number of non-zero entries in the given matrix
`static int`	`cardinality(Vector x)`	Returns the number of non-zero entries in the given vector
`static int[]`	`columnBandwidth(Matrix A)`	Finds the number of non-zero entries on each column
`static double[][]`	`getArray(Matrix A)`	Returns an array of arrays containing a copy of the given matrix.
`static double[]`	`getArray(Vector x)`	Returns a dense array containing a copy of the given vector
`static int`	`getNumSubDiagonals(Matrix A)`	Finds the number of diagonals below the main diagonal.
`static int`	`getNumSuperDiagonals(Matrix A)`	Finds the number of diagonals above the main diagonal.
`static Matrix`	`getSubMatrix(Matrix A, int[] row, int[] column)`	Returns a view into the given matrix.
`static Vector`	`getSubVector(Vector x, int[] index)`	Returns a view into the given vector.
`static DenseMatrix`	`identity(int size)`	Returns the identity matrix of the given size
`static int[]`	`index(int from, int to)`	Creates a continuous linear index.
`static int[]`	`index(int from, int stride, int to)`	Creates a strided linear index.
`static Vector`	`random(int size)`	Creates a random vector.
`static Matrix`	`random(int numRows, int numColumns)`	Creates a random matrix.
`static Matrix`	`random(Matrix A)`	Populates a matrix with random numbers drawn from a uniform distribution between 0 and 1
`static Vector`	`random(Vector x)`	Populates a vector with random numbers drawn from a uniform distribution between 0 and 1
`static int[]`	`rowBandwidth(Matrix A)`	Finds the number of non-zero entries on each row
`static Matrix`	`synchronizedMatrix(Matrix A)`	Returns a synchronized matrix which wraps the given matrix.
`static Matrix`	`synchronizedMatrixByColumns(Matrix A)`	Returns a synchronized matrix which wraps the given matrix.
`static Matrix`	`synchronizedMatrixByRows(Matrix A)`	Returns a synchronized matrix which wraps the given matrix.
`static Vector`	`synchronizedVector(Vector x)`	Returns a synchronized vector which wraps the given vector.
`static void`	`zeroColumns(Matrix A, double diagonal, int... column)`	Sets the selected columns of `A` equal zero, and puts `diagonal` on the diagonal of those columns.
`static void`	`zeroRows(Matrix A, double diagonal, int... row)`	Sets the selected rows of `A` equal zero, and puts `diagonal` on the diagonal of those rows.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - cardinality
```
public static int cardinality(Vector x)
```
    Returns the number of non-zero entries in the given vector
  - cardinality
```
public static int cardinality(Matrix A)
```
    Returns the number of non-zero entries in the given matrix
  - getArray
```
public static double[][] getArray(Matrix A)
```
    Returns an array of arrays containing a copy of the given matrix. Each array contains one row.
  - getArray
```
public static double[] getArray(Vector x)
```
    Returns a dense array containing a copy of the given vector
  - identity
```
public static DenseMatrix identity(int size)
```
    Returns the identity matrix of the given size
    
    Parameters:
    
    size - Number of rows/columns of the matrix
    
    Returns:
    
    Matrix of the given size, with ones on the main diagonal
  - random
```
public static Vector random(int size)
```
    Creates a random vector. Numbers are drawn from a uniform distribution between 0 and 1
    
    Parameters:
    
    size - Size of the vector
  - random
```
public static Vector random(Vector x)
```
    Populates a vector with random numbers drawn from a uniform distribution between 0 and 1
    
    Parameters:
    
    x - Vector to populate
  - random
```
public static Matrix random(int numRows,
                            int numColumns)
```
    Creates a random matrix. Numbers are drawn from a uniform distribution between 0 and 1
    
    Parameters:
    
    numRows - Number of rows
    
    numColumns - Number of columns
  - random
```
public static Matrix random(Matrix A)
```
    Populates a matrix with random numbers drawn from a uniform distribution between 0 and 1
    
    Parameters:
    
    A - Matrix to populate
  - synchronizedVector
```
public static Vector synchronizedVector(Vector x)
```
    Returns a synchronized vector which wraps the given vector. Only the set(int, double) and add(int, double) methods and their blocked versions are synchronized.
    Note: Do not use the wrapped vector for any operations besides matrix assembly, as these operations may be very slow.
    
    Parameters:
    
    x - Vector to be wrapped
    
    Returns:
    
    A thin wrapper around x
  - synchronizedMatrix
```
public static Matrix synchronizedMatrix(Matrix A)
```
    Returns a synchronized matrix which wraps the given matrix. Only the set(int, int, double) and add(int, int, double) methods and their blocked versions are synchronized.
    Note: Do not use the wrapped matrix for any operations besides matrix assembly, as these operations may be very slow.
    
    Parameters:
    
    A - Matrix to be wrapped
    
    Returns:
    
    A thin wrapper around A
  - synchronizedMatrixByRows
```
public static Matrix synchronizedMatrixByRows(Matrix A)
```
    Returns a synchronized matrix which wraps the given matrix. Only the set(int, int, double) and add(int, int, double) methods and their blocked versions are synchronized.
    The locking provided is finer than the locking of the whole matrix, as different threads can access different rows simultaneous, while only one thread can access a given row at a time. Use this for row-major matrices, not for column-major matrices.
    Note: Do not use the wrapped matrix for any operations besides matrix assembly, as these operations may be very slow.
    
    Parameters:
    
    A - Matrix to be wrapped
    
    Returns:
    
    A thin wrapper around A. Individual rows are locked
  - synchronizedMatrixByColumns
```
public static Matrix synchronizedMatrixByColumns(Matrix A)
```
    Returns a synchronized matrix which wraps the given matrix. Only the set(int, int, double) and add(int, int, double) methods and their blocked versions are synchronized.
    The locking provided is finer than the locking of the whole matrix, as different threads can access different columns simultaneous, while only one thread can access a given column at a time. Use this for column-major matrices, not for row-major matrices.
    Note: Do not use the wrapped matrix for any operations besides matrix assembly, as these operations may be very slow.
    
    Parameters:
    
    A - Matrix to be wrapped
    
    Returns:
    
    A thin wrapper around A. Individual columns are locked
  - getSubMatrix
```
public static Matrix getSubMatrix(Matrix A,
                                  int[] row,
                                  int[] column)
```
    Returns a view into the given matrix. This view is only for easing some matrix-assembly cases, not for general use. To extract a more higher-performing and general matrix, create a copy of the submatrix. The result is a DenseMatrix.
    
    Parameters:
    
    A - Matrix to create view on
    
    row - Rows to access. Must be within the bounds of A
    
    column - Columns to access. Must be within the bounds of A
    
    Returns:
    
    Submatrix of A. Changing it will change the backing matrix
  - getSubVector
```
public static Vector getSubVector(Vector x,
                                  int[] index)
```
    Returns a view into the given vector. This view is only for easing some vector-assembly cases, not for general use. To extract a more higher-performing and general vector, create a copy of the subvector. The result is a DenseVector.
    
    Parameters:
    
    x - Vector to create view on
    
    index - Indices to access. Must be within the bounds of x
    
    Returns:
    
    Submatrix of x. Changing it will change the backing matrix
  - index
```
public static int[] index(int from,
                          int to)
```
    Creates a continuous linear index.
    
    Parameters:
    
    from - Start, inclusive
    
    to - Stop, exclusive
  - index
```
public static int[] index(int from,
                          int stride,
                          int to)
```
    Creates a strided linear index.
    
    Parameters:
    
    from - Start, inclusive
    
    stride - stride=1 for continuous. Negative strides are allowed
    
    to - Stop, exclusive
  - rowBandwidth
```
public static int[] rowBandwidth(Matrix A)
```
    Finds the number of non-zero entries on each row
  - columnBandwidth
```
public static int[] columnBandwidth(Matrix A)
```
    Finds the number of non-zero entries on each column
  - getNumSubDiagonals
```
public static int getNumSubDiagonals(Matrix A)
```
    Finds the number of diagonals below the main diagonal. Useful for converting a general matrix into a banded matrix
  - getNumSuperDiagonals
```
public static int getNumSuperDiagonals(Matrix A)
```
    Finds the number of diagonals above the main diagonal. Useful for converting a general matrix into a banded matrix
  - zeroRows
```
public static void zeroRows(Matrix A,
                            double diagonal,
                            int... row)
```
    Sets the selected rows of A equal zero, and puts diagonal on the diagonal of those rows. Useful for enforcing boundary conditions
  - zeroColumns
```
public static void zeroColumns(Matrix A,
                               double diagonal,
                               int... column)
```
    Sets the selected columns of A equal zero, and puts diagonal on the diagonal of those columns. Useful for enforcing boundary conditions

Class Matrices

Method Summary

Methods inherited from class java.lang.Object

Method Detail

cardinality

cardinality

getArray

getArray

identity

random

random

random

random

synchronizedVector

synchronizedMatrix

synchronizedMatrixByRows

synchronizedMatrixByColumns

getSubMatrix

getSubVector

index

index

rowBandwidth

columnBandwidth

getNumSubDiagonals

getNumSuperDiagonals

zeroRows

zeroColumns