Package org.djutils.math.functions

Class Constant

java.lang.Object
org.djutils.math.functions.Constant
All Implemented Interfaces:
Comparable<MathFunction>, Function<Double,Double>, MathFunction
public class Constant extends Object implements MathFunction
Constant value function; f(x) → c where c ∈ ℝ. Can also be implemented with PowerFunction, but this is much more readable and efficient.

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Author:
Alexander Verbraeck, Peter Knoppers, Wouter Schakel

  • Field Details

    • ZERO

      public static final Constant ZERO
      The constant value function that is always zero and has infinite domain.

    • ONE

      public static final Constant ONE
      The constant value function that is always one and has infinite domain.

  • Constructor Details

    • Constant

      public Constant(double value)
      Create a new constant value function F(x).
      Parameters:
      value - the value at any x

  • Method Details

    • apply

      public Double apply(Double x)
      Specified by:
      apply in interface Function<Double,Double>

    • getDerivative

      public Constant getDerivative()
      Description copied from interface: MathFunction
      Returns the derivative of the data with respect to fractional length.
      Specified by:
      getDerivative in interface MathFunction
      Returns:
      derivative of this MathFunction

    • simplify

      public MathFunction simplify()
      Description copied from interface: MathFunction
      Attempts to find a simplified version of this MathFunction (e.g. replace 1 - 5 by -4).
      Specified by:
      simplify in interface MathFunction
      Returns:
      this, or a simplified version thereof

    • getScale

      public double getScale()
      Description copied from interface: MathFunction
      Get the scale factor of this MathFunction.
      Specified by:
      getScale in interface MathFunction
      Returns:
      the scale factor of this MathFunction

    • scaleBy

      public MathFunction scaleBy(double factor)
      Description copied from interface: MathFunction
      Incorporate a multiplication factor to this MathFunction.
      Specified by:
      scaleBy in interface MathFunction
      Parameters:
      factor - the factor to incorporate
      Returns:
      a new MathFunction that yields the same result as the original function multiplied by the factor

    • sortPriority

      public int sortPriority()
      Description copied from interface: MathFunction
      Sorting priority of this type of MathFunction (low values shall sort before higher).
      Specified by:
      sortPriority in interface MathFunction
      Returns:
      sorting priority of this type of MathFunction

    • compareWithinSubType

      public int compareWithinSubType(MathFunction other)
      Description copied from interface: MathFunction
      Determine sorting order among instances of a particular sub type of MathFunction. The sorting order should sort MathFunctions that may be combined next to one another. Because MathFunctions are also used in SortedSets, this comparator may return 0 if and only if this and other are entirely equal!
      Specified by:
      compareWithinSubType in interface MathFunction
      Parameters:
      other - the other MathFunction that must be of the same type
      Returns:
      int; < 0 when this sorts before other; > 0 when this sorts after other; 0 when this and other are identical

    • mergeAdd

      public MathFunction mergeAdd(MathFunction other)
      Description copied from interface: MathFunction
      This MathFunction is added to another; try to replace both by a combined MathFunction.
      Specified by:
      mergeAdd in interface MathFunction
      Parameters:
      other - the other MathFunction
      Returns:
      combined MathFunction, or null when the two could not be combined

    • mergeMultiply

      public MathFunction mergeMultiply(MathFunction other)
      Description copied from interface: MathFunction
      This MathFunction is multiplied by another; try to replace both by a combined MathFunction.
      Specified by:
      mergeMultiply in interface MathFunction
      Parameters:
      other - the other MathFunction
      Returns:
      combined MathFunction, or null when the two could not be combined

    • getKnotReport

      public KnotReport getKnotReport(Interval<?> interval)
      Description copied from interface: MathFunction
      Report what is known about knots of this MathFunction in some Interval. The report does not take chained functions into account.
      Specified by:
      getKnotReport in interface MathFunction
      Parameters:
      interval - the Interval on which knowledge of knots is requested
      Returns:
      summary of what is known about knots in the Interval

    • getKnots

      public SortedSet<Double> getKnots(Interval<?> interval)
      Description copied from interface: MathFunction
      Report all knots of this MathFunction in some Interval. Throws IllegalStateException when the number of knots in the Interval is not known, or infinite.
      Specified by:
      getKnots in interface MathFunction
      Parameters:
      interval - the Interval over which the knots must be reported
      Returns:
      all the knots of this MathFunction in the requested Interval

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object