Constructor Detail

• JacobiPreconditioner

  public JacobiPreconditioner(double[] diag,
                      boolean deep)

  Creates a new instance of this class.

  Parameters:

  diag - the diagonal coefficients of the linear operator to be preconditioned

  deep - true if a deep copy of the above array should be performed

Method Detail

• create

  public static JacobiPreconditioner create(RealLinearOperator a)
                                     throws NonSquareOperatorException

  Creates a new instance of this class. This method extracts the diagonal coefficients of the specified linear operator. If a does not extend AbstractRealMatrix, then the coefficients of the underlying matrix are not accessible, coefficient extraction is made by matrix-vector products with the basis vectors (and might therefore take some time). With matrices, direct entry access is carried out.

  Parameters:

  a - the linear operator for which the preconditioner should be built

  Returns:

  the diagonal preconditioner made of the inverse of the diagonal coefficients of the specified linear operator

  Throws:

  NonSquareOperatorException - if a is not square

• getColumnDimension

  public int getColumnDimension()

  Returns the dimension of the domain of this operator.

  Specified by:

  getColumnDimension in class RealLinearOperator

  Returns:

  the number of columns of the underlying matrix

• getRowDimension

  public int getRowDimension()

  Returns the dimension of the codomain of this operator.

  Specified by:

  getRowDimension in class RealLinearOperator

  Returns:

  the number of rows of the underlying matrix

• operate

  public RealVector operate(RealVector x)

  Returns the result of multiplying this by the vector x.

  Specified by:

  operate in class RealLinearOperator

  Parameters:

  x - the vector to operate on

  Returns:

  the product of this instance with x

• sqrt

  public RealLinearOperator sqrt()

  Returns the square root of this diagonal operator. More precisely, this method returns P = diag(1 / √A₁₁, 1 / √A₂₂, …).

  Returns:

  the square root of this preconditioner

  Since:

  3.1