Package ptolemy.math

Class Interpolation

  • public class Interpolation
extends java.lang.Object
    This class provides algorithms to do interpolation. Currently, zero, first, and third order interpolations are supported. These are the interpolation orders most often used in practice. zero order interpolation holds the last reference value; first order does linear interpolation; and third order interpolation is based on the Hermite curves in chapter 11 of "Computer Graphic, Principles and Practice", by Foley, van Dam, Feiner and Hughes, 2nd ed. in C, 1996.

    The setValues() method specifies the reference values as a double array. setIndexes() specifies the indexes of those values as an int array. These two arrays must have the same length, and the indexes must be increasing and non-negative; otherwise an exception will be thrown. The values are periodic if a positive period is set by setPeriod(). In this case, the period must be greater than the largest index, and values within the index range 0 to (period-1) are repeated indefinitely. If the period is zero, the values are not periodic, and the values outside the range of the indexes are considered to be 0.0. The interpolation order is set by setOrder().

    The default reference values are {1.0, 0.0} and the indexes are {0, 1}. The default period is 2 and the order is 0.

    Since:
    Ptolemy II 0.4
    Version:
    $Id$
    Author:
    Sarah Packman, Yuhong Xiong
    Pt.AcceptedRating:
    red (cxh)
    Pt.ProposedRating:
    Yellow (yuhong)

    • Constructor Summary

      Constructors 
      Constructor Description
      Interpolation()
      Construct an instance of Interpolation using the default parameters.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int[] getIndexes()
      Return the reference indexes.
      int getOrder()
      Return the interpolation order.
      int getPeriod()
      Return the value repetition period.
      double[] getValues()
      Return the reference values.
      double interpolate​(int index)
      Return the interpolation result for the specified index.
      void setIndexes​(int[] indexes)
      Set the reference indexes.
      void setOrder​(int order)
      Set the interpolation order.
      void setPeriod​(int period)
      Set the value repetition period.
      void setValues​(double[] values)
      Set the reference values.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • Interpolation

        public Interpolation()
        Construct an instance of Interpolation using the default parameters.

    • Method Detail

      • getIndexes

        public int[] getIndexes()
        Return the reference indexes.
        Returns:
        An int array.
        See Also:
        setIndexes(int[])

      • getOrder

        public int getOrder()
        Return the interpolation order.
        Returns:
        An int.
        See Also:
        setOrder(int)

      • getPeriod

        public int getPeriod()
        Return the value repetition period.
        Returns:
        An int.
        See Also:
        setPeriod(int)

      • getValues

        public double[] getValues()
        Return the reference values.
        Returns:
        An double array.
        See Also:
        setValues(double[])

      • interpolate

        public double interpolate​(int index)
        Return the interpolation result for the specified index.
        Parameters:
        index - The point of interpolation. Can be negative
        Returns:
        A double.
        Throws:
        java.lang.IllegalStateException - If the index and value arrays do not have the same length, or the period is not 0 and not greater than the largest index.

      • setIndexes

        public void setIndexes​(int[] indexes)
        Set the reference indexes.
        Parameters:
        indexes - An int array.
        Throws:
        java.lang.IllegalArgumentException - If the argument array is not increasing and non-negative.
        See Also:
        getIndexes()

      • setOrder

        public void setOrder​(int order)
        Set the interpolation order.
        Parameters:
        order - An int.
        Throws:
        java.lang.IllegalArgumentException - If the order is not 0, 1, or 3.
        See Also:
        getOrder()

      • setPeriod

        public void setPeriod​(int period)
        Set the value repetition period.
        Parameters:
        period - An int.
        Throws:
        java.lang.IllegalArgumentException - If the period is negative.
        See Also:
        getPeriod()

      • setValues

        public void setValues​(double[] values)
        Set the reference values.
        Parameters:
        values - A double array.
        See Also:
        getValues()