Module ojalgo
Package org.ojalgo.matrix.store

Class R064CSC

java.lang.Object
org.ojalgo.matrix.store.AbstractStore<Double>
org.ojalgo.matrix.store.FactoryStore<Double>
org.ojalgo.matrix.store.CompressedSparseR064
org.ojalgo.matrix.store.R064CSC
All Implemented Interfaces:
Group, Group.Additive<MatrixStore<Double>>, NormedVectorSpace<MatrixStore<Double>,Double>, Operation, Operation.Addition<MatrixStore<Double>>, Operation.Multiplication<MatrixStore<Double>>, Operation.Subtraction<MatrixStore<Double>>, ScalarOperation, ScalarOperation.Addition<MatrixStore<Double>,Double>, ScalarOperation.Division<MatrixStore<Double>,Double>, ScalarOperation.Multiplication<MatrixStore<Double>,Double>, ScalarOperation.Subtraction<MatrixStore<Double>,Double>, VectorSpace<MatrixStore<Double>,Double>, Matrix2D<Double,MatrixStore<Double>>, ElementsSupplier<Double>, MatrixStore<Double>, SparseStructure2D, Access1D<Double>, Access1D.Aggregatable<Double>, Access1D.Collectable<Double,Mutate1D>, Access1D.Sliceable<Double>, Access1D.Visitable<Double>, Access2D<Double>, Access2D.Aggregatable<Double>, Access2D.Collectable<Double,TransformableRegion<Double>>, Access2D.Sliceable<Double>, Access2D.Visitable<Double>, Operate2D<Double,ElementsSupplier<Double>>, Structure1D, Structure2D, Structure2D.Logical<Access2D<Double>,MatrixStore<Double>>, Structure2D.ReducibleTo1D<ElementsSupplier<Double>>
public final class R064CSC extends CompressedSparseR064
A compressed sparse column (CSC) matrix store implementation for double precision values. This format is efficient for column-wise operations and matrix-vector multiplication.

The CSC format uses three arrays to store the matrix:

  • values[] - stores the non-zero values
  • rowIndices[] - stores the row index for each non-zero value
  • columnPointers[] - stores the starting position in values/rowIndices arrays for each column

This format is particularly efficient for:

  • Column-wise access and operations
  • Matrix-vector multiplication
  • Iterating over non-zero elements column by column

  • Constructor Details

    • R064CSC

      R064CSC(int nbRows, int nbCols, double[] elementValues, int[] rowIndices, int[] columnPointers)
      Creates a new CSC matrix store.
      Parameters:
      elementValues - The non-zero values
      rowIndices - The row index for each non-zero value
      columnPointers - The starting position in elementValues/rowIndices for each column
      rows - The number of rows in the matrix
      cols - The number of columns in the matrix

  • Method Details

    • btran

      public static void btran(R064CSC mtrxL, int r, PhysicalStore<Double> arg)
      Assumes mtrxL is unit lower/left triangular, with the unit diagonal not stored.

    • ftran

      public static void ftran(R064CSC mtrxL, int r, PhysicalStore<Double> arg)
      Assumes mtrxL is unit lower/left triangular, with the unit diagonal not stored.

    • doubleValue

      public double doubleValue(int row, int col)
      Gets the value at the specified row and column. Returns 0.0 if the element is not stored (i.e., is zero).
      Parameters:
      row - The row index
      col - The column index
      Returns:
      The value at the specified position, or 0.0 if not stored

    • firstInColumn

      public int firstInColumn(int col)
      Description copied from interface: Structure2D
      The default value is simply 0, and if all elements are zeros then this.countRows().
      Parameters:
      col - The column index
      Returns:
      The row index of the first non-zero element in the specified column

    • firstInRow

      public int firstInRow(int row)
      Description copied from interface: Structure2D
      The default value is simply 0, and if all elements are zeros then this.countColumns().
      Returns:
      The column index of the first non-zero element in the specified row

    • limitOfColumn

      public int limitOfColumn(int col)
      Description copied from interface: Structure2D
      The default value is simply this.countRows(), and if all elements are zeros then 0.
      Specified by:
      limitOfColumn in interface Structure2D
      Overrides:
      limitOfColumn in class AbstractStore<Double>
      Returns:
      The row index of the first zero element, after all non-zeros, in the specified column (index of the last non-zero + 1)

    • limitOfRow

      public int limitOfRow(int row)
      Description copied from interface: Structure2D
      The default value is simply this.countColumns(), and if all elements are zeros then 0.
      Specified by:
      limitOfRow in interface Structure2D
      Overrides:
      limitOfRow in class AbstractStore<Double>
      Returns:
      The column index of the first zero element, after all non-zeros, in the specified row (index of the last non-zero + 1)

    • multiply

      public void multiply(Access1D<Double> right, TransformableRegion<Double> target)
      Performs matrix-vector multiplication using the CSC format. This implementation is optimized for the CSC format by iterating over non-zero elements column by column and accumulating the results.
      Parameters:
      right - The vector to multiply with
      target - The target vector to store the result

    • nonzeros

      public R064CSC.NonZeroView nonzeros()
      Description copied from interface: Access1D
      Similar to Access1D.elements() but avoids elements that are structurally known to be zero. (That does not eliminate all zero-values from this view.) With an arbitrary (dense) unstructured implementation the Access1D.nonzeros() and Access1D.elements() methods do the same thing! Only some specific implementations are able to actually exploit structure/sparsity to view fewer elements.

    • toCSC

      public R064CSC toCSC()

    • toCSR

      public R064CSR toCSR()