Interface Vector

All Superinterfaces:
Iterable<VectorEntry>, Serializable
All Known Subinterfaces:
ISparseVector
All Known Implementing Classes:
AbstractVector, DenseVector, DistVector, SparseVector

public interface Vector extends Iterable<VectorEntry>, Serializable
Basic vector interface. It holds doubles in an array, and is used alongside Matrix in numerical computations. Implementing classes decides on the actual storage.

Basic operations

Use size to get the vector size. get(int) gets an element, and there are corresponding set(int,double) and add(int,double) methods as well. Note that vector indices are zero-based (typical for Java and C). This means that they range from 0 to size-1. It is legal to have size equal zero.

Other basic operations are zero which zeros all the entries of the vector, which can be cheaper than either zeroing the vector manually, or creating a new vector, and the operation copy which creates a deep copy of the vector. This copy has separate storage, but starts with the same contents as the current vector.

Iterators

The vector interface extends Iterable, and the iterator returns a VectorEntry which contains current index and entry value. Note that the iterator may skip non-zero entries. Using an iterator, many simple and efficient algorithms can be created. The iterator also permits changing values in the vector, however only non-zero entries can be changed.

Basic linear algebra

A selection of basic linear algebra operations are available. To ensure high efficiency, little or no internal memory allocation is done, and the user is required to supply the output arguments.

The operations available include:

Additions
Vectors can be added to each other, even if their underlying vector structures are incompatible
Scaling
Scalar multiplication (scaling) of a whole vector
Norms
Both innerproducts and norms can be computed. Several common norms are supported
  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static enum 
    Supported vector-norms.
  • Method Summary

    Modifier and Type
    Method
    Description
    add(double alpha, Vector y)
    x = alpha*y + x
    void
    add(int index, double value)
    x(index) += value
    x = y + x
    Creates a deep copy of the vector
    double
    xT*y
    double
    get(int index)
    Returns x(index)
    double
    Computes the given norm of the vector
    scale(double alpha)
    x=alpha*x
    set(double alpha, Vector y)
    x=alpha*y
    void
    set(int index, double value)
    x(index) = value
    x=y
    int
    Size of the vector
    Zeros all the entries in the vector, while preserving any underlying structure

    Methods inherited from interface java.lang.Iterable

    forEach, iterator, spliterator
  • Method Details

    • size

      int size()
      Size of the vector
    • set

      void set(int index, double value)
      x(index) = value
    • add

      void add(int index, double value)
      x(index) += value
    • get

      double get(int index)
      Returns x(index)
    • copy

      Vector copy()
      Creates a deep copy of the vector
    • zero

      Vector zero()
      Zeros all the entries in the vector, while preserving any underlying structure
    • scale

      Vector scale(double alpha)
      x=alpha*x
      Returns:
      x
    • set

      Vector set(Vector y)
      x=y
      Returns:
      x
    • set

      Vector set(double alpha, Vector y)
      x=alpha*y
      Returns:
      x
    • add

      Vector add(Vector y)
      x = y + x
      Returns:
      x
    • add

      Vector add(double alpha, Vector y)
      x = alpha*y + x
      Returns:
      x
    • dot

      double dot(Vector y)
      xT*y
    • norm

      double norm(Vector.Norm type)
      Computes the given norm of the vector
      Parameters:
      type - The type of norm to compute