Package no.uib.cipr.matrix

Interface Vector

  • All Superinterfaces:
    java.lang.Iterable<VectorEntry>, java.io.Serializable
    All Known Subinterfaces:
    ISparseVector
    All Known Implementing Classes:
    AbstractVector, DenseVector, DistVector, SparseVector
    public interface Vector
extends java.lang.Iterable<VectorEntry>, java.io.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 class  Vector.Norm
      Supported vector-norms.

    • Method Summary

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

      • Methods inherited from interface java.lang.Iterable

        forEach, iterator, spliterator

    • Method Detail

      • 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​(double alpha,
           Vector y)
        x=alpha*y
        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