Package org.djutils.math.functions

Class Logarithm

java.lang.Object
org.djutils.math.functions.Logarithm
All Implemented Interfaces:
Comparable<MathFunction>, Function<Double,Double>, MathFunction
public class Logarithm extends Object implements MathFunction
Logarithms.

Copyright (c) 2024-2025 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://djutils.org. The DJUTILS project is distributed under a three-clause BSD-style license, which can be found at https://djutils.org/docs/license.html.

Author:
Alexander Verbraeck, Peter Knoppers, Wouter Schakel

  • Constructor Details

    • Logarithm

      public Logarithm()
      Natural logarithm; logarithm with base e.

    • Logarithm

      public Logarithm(double base)
      Logarithm with user specified base. The base is the value where the logarithm function has the value 1.0.
      Parameters:
      base - the base of the new logarithm

    • Logarithm

      public Logarithm(MathFunction chain)
      Natural logarithm of chained MathFunction.
      Parameters:
      chain - the chained MathFunction

    • Logarithm

      public Logarithm(MathFunction chain, double base)
      Logarithm of chained function and user specified base. The base is the value where the logarithm function has the value 1.0.
      Parameters:
      chain - the chained MathFunction
      base - the base

  • Method Details

    • apply

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

    • getDerivative

      public MathFunction 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

    • scaleBy

      public MathFunction scaleBy(double scaleFactor)
      Description copied from interface: MathFunction
      Incorporate a multiplication factor to this MathFunction.
      Specified by:
      scaleBy in interface MathFunction
      Parameters:
      scaleFactor - 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

    • 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