Package no.uib.cipr.matrix

Class LowerTriangPackMatrix

java.lang.Object
no.uib.cipr.matrix.AbstractMatrix
no.uib.cipr.matrix.LowerTriangPackMatrix
All Implemented Interfaces:
Iterable<MatrixEntry>, Matrix
Direct Known Subclasses:
UnitLowerTriangPackMatrix
public class LowerTriangPackMatrix extends AbstractMatrix
Lower triangular packed matrix. In contrast with LowerTriangDenseMatrix, this matrix exploits the sparsity by only storing about half the matrix. As such, the triangular matrix

a11      
a21 a22    
a31 a32 a33  
a41 a42 a43 a44

is packed as follows:

a11 a21 a31 a41 a22 a32 a42 a33 a43 a44

  • Constructor Details

    • LowerTriangPackMatrix

      public LowerTriangPackMatrix(int n)
      Constructor for LowerTriangPackMatrix
      Parameters:
      n - Size of the matrix. Since the matrix must be square, this equals both the number of rows and columns

    • LowerTriangPackMatrix

      public LowerTriangPackMatrix(Matrix A)
      Constructor for LowerTriangPackMatrix
      Parameters:
      A - Matrix to copy contents from. Only the entries of the relevant part are copied

    • LowerTriangPackMatrix

      public LowerTriangPackMatrix(Matrix A, boolean deep)
      Constructor for LowerTriangPackMatrix
      Parameters:
      A - Matrix to copy contents from. Only the entries of the relevant part are copied
      deep - True if the copy is deep, else false (giving a shallow copy). For shallow copies, A must be a packed matrix

  • Method Details

    • add

      public void add(int row, int column, double value)
      Description copied from interface: Matrix
      A(row,column) += value
      Specified by:
      add in interface Matrix
      Overrides:
      add in class AbstractMatrix

    • set

      public void set(int row, int column, double value)
      Description copied from interface: Matrix
      A(row,column) = value
      Specified by:
      set in interface Matrix
      Overrides:
      set in class AbstractMatrix

    • get

      public double get(int row, int column)
      Description copied from interface: Matrix
      Returns A(row,column)
      Specified by:
      get in interface Matrix
      Overrides:
      get in class AbstractMatrix

    • copy

      public LowerTriangPackMatrix copy()
      Description copied from interface: Matrix
      Creates a deep copy of the matrix
      Specified by:
      copy in interface Matrix
      Overrides:
      copy in class AbstractMatrix
      Returns:
      A

    • mult

      public Vector mult(double alpha, Vector x, Vector y)
      Description copied from interface: Matrix
      y = alpha*A*x
      Specified by:
      mult in interface Matrix
      Overrides:
      mult in class AbstractMatrix
      Parameters:
      x - Vector of size A.numColumns()
      y - Vector of size A.numRows()
      Returns:
      y

    • transMult

      public Vector transMult(double alpha, Vector x, Vector y)
      Description copied from interface: Matrix
      y = alpha*AT*x
      Specified by:
      transMult in interface Matrix
      Overrides:
      transMult in class AbstractMatrix
      Parameters:
      x - Vector of size A.numRows()
      y - Vector of size A.numColumns()
      Returns:
      y

    • solve

      public Matrix solve(Matrix B, Matrix X)
      Description copied from interface: Matrix
      X = A\B. Not all matrices support this operation, those that do not throw UnsupportedOperationException. Note that it is often more efficient to use a matrix decomposition and its associated solver
      Specified by:
      solve in interface Matrix
      Overrides:
      solve in class AbstractMatrix
      Parameters:
      B - Matrix with the same number of rows as A, and the same number of columns as X
      X - Matrix with a number of rows equal A.numColumns(), and the same number of columns as B
      Returns:
      X

    • solve

      public Vector solve(Vector b, Vector x)
      Description copied from interface: Matrix
      x = A\b. Not all matrices support this operation, those that do not throw UnsupportedOperationException. Note that it is often more efficient to use a matrix decomposition and its associated solver
      Specified by:
      solve in interface Matrix
      Overrides:
      solve in class AbstractMatrix
      Parameters:
      b - Vector of size A.numRows()
      x - Vector of size A.numColumns()
      Returns:
      x

    • transSolve

      public Matrix transSolve(Matrix B, Matrix X)
      Description copied from interface: Matrix
      X = AT\B. Not all matrices support this operation, those that do not throw UnsupportedOperationException. Note that it is often more efficient to use a matrix decomposition and its associated transpose solver
      Specified by:
      transSolve in interface Matrix
      Overrides:
      transSolve in class AbstractMatrix
      Parameters:
      B - Matrix with a number of rows equal A.numColumns(), and the same number of columns as X
      X - Matrix with the same number of rows as A, and the same number of columns as B
      Returns:
      X

    • transSolve

      public Vector transSolve(Vector b, Vector x)
      Description copied from interface: Matrix
      x = AT\b. Not all matrices support this operation, those that do not throw UnsupportedOperationException. Note that it is often more efficient to use a matrix decomposition and its associated solver
      Specified by:
      transSolve in interface Matrix
      Overrides:
      transSolve in class AbstractMatrix
      Parameters:
      b - Vector of size A.numColumns()
      x - Vector of size A.numRows()
      Returns:
      x

    • iterator

      public Iterator<MatrixEntry> iterator()
      Specified by:
      iterator in interface Iterable<MatrixEntry>
      Overrides:
      iterator in class AbstractMatrix

    • getData

      public double[] getData()
      Returns the matrix contents. Ordering depends on the underlying storage assumptions

    • set

      public Matrix set(Matrix B)
      Description copied from interface: Matrix
      A=B. The matrices must be of the same size
      Specified by:
      set in interface Matrix
      Overrides:
      set in class AbstractMatrix
      Returns:
      A

    • zero

      public Matrix zero()
      Description copied from interface: Matrix
      Zeros all the entries in the matrix, while preserving any underlying structure. Useful for general, unstructured matrices.
      Specified by:
      zero in interface Matrix
      Overrides:
      zero in class AbstractMatrix
      Returns:
      A