Warning, file /education/kmplot/kmplot/function.h was not indexed or was modified since last indexation (in which case cross-reference links may be missing, inaccurate or erroneous).

 /*
     KmPlot - a math. function plotter for the KDE-Desktop
 
     SPDX-FileCopyrightText: 1998, 1999, 2000, 2002 Klaus-Dieter Möller <kd.moeller@t-online.de>
     SPDX-FileCopyrightText: 2006 David Saxton <david@bluehaze.org>
 
     This file is part of the KDE Project.
     KmPlot is part of the KDE-EDU Project.
 
     SPDX-License-Identifier: GPL-2.0-or-later
 
 */
 
 #ifndef FUNCTION_H
 #define FUNCTION_H
 
 #include "vector.h"
 
 #include <QByteArray>
 #include <QColor>
 #include <QFlags>
 #include <QGradient>
 #include <QVector>
 
 class Equation;
 class Function;
 class Plot;
 
 /**
  * Maximum number of plus-minus-s; each added one doubles the number of combinations
  * which quickly grows. So put a bound on the number allowed.
  */
 extern int MAX_PM;
 
 /**
  * This stores a string which evaluates directly to a number (i.e. without any
  * input variables such as x).
  */
 class Value
 {
 public:
     /**
      * Initializes Value with \p expression.
      * This will have the value 0 if \p expression is empty or unparsable.
      */
     Value(const QString &expression = QString());
     /**
      * Converts \p value to a string (see Parser::number) and initializes
      * this with the \p value.
      */
     explicit Value(double value);
 
     /**
      * @return The value of the current expression.
      */
     double value() const
     {
         return m_value;
     }
     /**
      * @return The current expression.
      */
     QString expression() const
     {
         return m_expression;
     }
     /**
      * Sets the current expression. If the expression could be evaluated
      * (i.e. no errors), then value is updated, the expression is saved and
      * true is returned. Otherwise, just returns false.
      */
     bool updateExpression(const QString &expression);
     /**
      * Converts \p value to a string (see Parser::number) and uses it for
      * the current expression.
      */
     void updateExpression(double value);
     /**
      * This checks if the expression strings (and hence values) are
      * identical.
      */
     bool operator==(const Value &other) const;
     /**
      * Checks for inequality.
      */
     bool operator!=(const Value &other) const
     {
         return !((*this) == other);
     }
 
 protected:
     QString m_expression;
     double m_value;
 };
 
 /**
  * Stores details of the appearance of a plot of a function (e.g. its
  * derivative or integral).
  */
 class PlotAppearance
 {
 public:
     PlotAppearance();
 
     // NOTE: When adding more members to this class, remember to update
     // the function PlotAppearance::operator!= and the functions in
     // KmPlotIO for saving / loading the plot appearance
 
     double lineWidth; ///< line width in mm
     QColor color; ///< color that the plot will be drawn in
     Qt::PenStyle style; ///< pen style (e.g. dolif, dashes, dotted, etc)
     QGradient gradient; ///< the gradient if useGradient is true
     bool useGradient : 1; ///< for plots with parameters, whether to use gradient instead of color
     bool showExtrema : 1; ///< for cartesian functions, whether to show the extreme values of the function
     bool showTangentField : 1; ///< whether to draw the tangent field (for differential equations
     bool visible : 1; ///< whether to display this plot
     bool showPlotName : 1; ///< whether to show the name of the plot on the graph
 
     bool operator!=(const PlotAppearance &other) const;
 
     /**
      * Converts a pen style to a string (for non-displaying uses such as
      * saving to file).
      */
     static QString penStyleToString(Qt::PenStyle style);
     /**
      * Converts a string (as returned by penStyleTostring) to a pen style.
      */
     static Qt::PenStyle stringToPenStyle(const QString &style);
 };
 
 /**
  * Used in differential equations; contains the initial conditions and the
  * currently calculated value (used as a cache).
  */
 class DifferentialState
 {
 public:
     DifferentialState();
     explicit DifferentialState(int order);
 
     /**
      * Resizes y, y0. Also calls resetToInitial.
      */
     void setOrder(int order);
     /**
      * Sets y=y0, x=x0.
      */
     void resetToInitial();
 
     Value x0; ///< the initial x-value
     QVector<Value> y0; ///< the value of ( f, f', f'', ...., f^(n) ) at x0
     double x; ///< the current x value
     Vector y; ///< the value of ( f, f', f'', ...., f^(n) ) at x
 
     /**
      * Whether the initial conditions and current state are the same.
      */
     bool operator==(const DifferentialState &other) const;
 };
 
 class DifferentialStates
 {
 public:
     DifferentialStates();
 
     /**
      * For Cartesian equations, can only have one state (for integrals).
      */
     void setUniqueState(bool unique);
     /**
      * \see order()
      */
     void setOrder(int order);
     /**
      * Creates a differential state. If this is for a Cartesian equation
      * and there is already a differential state, then that will be
      * returned instead, since a Cartesian equation can only have one
      * differential state.
      */
     DifferentialState *add();
     /**
      * The order of the differential equations, e.g. "f''(x) = -f" is of
      * order 2.
      */
     int order() const
     {
         return m_order;
     }
     /**
      * The number of differential states.
      */
     int size() const
     {
         return m_data.size();
     }
     /**
      * Calls DifferentialState::resetToInitial for each state; i.e. resets
      * the cached information about the state of the differential equation.
      */
     void resetToInitial();
     /**
      * The maximum step-size (and hence minimum precision) used in the RK4
      * method (see XParser::differential). Of course, a smaller step size
      * may be used in the visible section of a differential plot.
      */
     Value step() const
     {
         return m_step;
     }
     /**
      * \see maximumStep();
      * \return whether could successfully set the step, i.e. that it is
      * strictly positive.
      */
     bool setStep(const Value &step);
 
     bool operator==(const DifferentialStates &other) const
     {
         return (m_data == other.m_data) && (m_step == other.m_step);
     }
     bool operator!=(const DifferentialStates &other) const
     {
         return !(*this == other);
     }
     DifferentialState &operator[](int i)
     {
         return m_data[i];
     }
     const DifferentialState &operator[](int i) const
     {
         return m_data[i];
     }
     void remove(int i)
     {
         m_data.remove(i);
     }
     void remove(int i, int count)
     {
         m_data.remove(i, count);
     }
     void removeAll()
     {
         m_data.clear();
     }
 
 protected:
     QVector<DifferentialState> m_data;
     int m_order;
     bool m_uniqueState;
     Value m_step;
 };
 
 /**
  * This is the non-visual mathematical expression.
  * \note when adding new member variables, make sure to update operator !=
  * and operator =.
  */
 class Equation
 {
 public:
     enum Type {
         Constant,
         Cartesian,
         ParametricX,
         ParametricY,
         Polar,
         Implicit,
         Differential,
     };
 
     Equation(Type type, Function *parent);
     ~Equation();
 
     /// The type of function
     Type type() const
     {
         return m_type;
     }
     /**
      * \return whether this Equation has different user-entered values to
      * the \p other equation.
      */
     bool operator!=(const Equation &other);
     /**
      * Assigns the value in \p other to this equation.
      */
     Equation &operator=(const Equation &other);
     /**
      * Pointer to the allocated memory for the tokens.
      */
     QByteArray mem;
     /**
      * Array index to the token.
      */
     char *mptr;
     /**
      * @return a pointer to Function parent of this Equation.
      */
     Function *parent() const
     {
         return m_parent;
     }
     /**
      * @return the name of the function, e.g. for the cartesian function
      * f(x)=x^2, this would return "f".
      */
     QString name(bool removePrimes = true) const;
     /**
      * \return a list of variables, e.g. {x} for "f(x)=y", and {x,y,k} for
      * "f(x,y,k)=(x+k)(y+k)".
      */
     QStringList variables() const
     {
         return m_variables;
     }
     /**
      * \return whether the function accepts a parameter in addition to the x
      * (and possibly y) variables.
      */
     bool usesParameter() const
     {
         return m_usesParameter;
     }
     /**
      * \return the name of the parameter variable (or a blank string if a
      * parameter is not used).
      */
     QString parameterName() const;
     /**
      * The full function expression, e.g. "f(x,k)=(x+k)(x-k)".
      */
     QString fstr() const
     {
         return m_fstr;
     }
     /**
      * @see fstr()
      * @param string the equation
      * @param error if non-null, then will be set to the parser error (or
      * success).
      * @param errorPosition the error position
      * @param force Update the internal equation string even if it could not
      * be parsed correctly. Used in opening old files, for example, in case
      * something internal to kmplot has changed that results in the equation
      * no longer being parsable.
      * @return whether \p fstr could be parsed correctly. Note that if it
      * was not parsed correctly, then this will return false and this class
      * will not be updated.
      */
     bool setFstr(const QString &string, int *error = 0, int *errorPosition = 0, bool force = false);
     /**
      * \return true if the fstr looks like "f(x) = ..."
      * \return false if the fstr looks like "y = ..." (note that this
      * depends on the type of equation, so if this is a Cartesian equation
      * and the fstr looks like "a = ..." (not y) then it'll be considered a
      * function, even if it isn't a very useful one.
      */
     bool looksLikeFunction() const;
     /**
      * \return the order of the differential equations.
      */
     int order() const;
     /**
      * \return the number of plus-minus symbols in the equation.
      */
     int pmCount() const;
 
     /// For differential equations, all the states
     DifferentialStates differentialStates;
 
     /**
      * The current plus-minus signature (true for plus, false for minus).
      */
     QVector<bool> pmSignature() const
     {
         return m_pmSignature;
     }
     /**
      * \see pmSignature.
      */
     void setPMSignature(QVector<bool> pmSignature);
 
 protected:
     /**
      * Updates m_variables.
      */
     void updateVariables();
 
     bool m_usesParameter;
     const Type m_type;
     QString m_fstr;
     Function *m_parent;
     QVector<bool> m_pmSignature;
     /**
      * Cached list of variables. Updated when setFstr is called.
      */
     QStringList m_variables;
 };
 
 /**
  * Which parameters to use and how.
  */
 class ParameterSettings
 {
 public:
     ParameterSettings();
 
     bool operator==(const ParameterSettings &other) const;
     bool operator!=(const ParameterSettings &other) const
     {
         return !((*this) == other);
     }
 
     bool animating; ///< if true, then useSlider and useList are ignored, parameter value is assumed to be updated
     bool useSlider;
     int sliderID;
     bool useList;
     QList<Value> list;
 };
 
 /**
  * Uniquely identifies a parameter (which could be from the list of Values
  * stored in a Function or from a Slider.
  */
 class Parameter
 {
 public:
     enum Type {
         Unknown,
         Animated,
         Slider,
         List,
     };
     explicit Parameter(Type type = Unknown);
 
     Type type() const
     {
         return m_type;
     }
     /**
      * The slider ID specifies which slider to use (e.g. "2" specifies the
      * third slider).
      */
     void setSliderID(int id)
     {
         m_sliderID = id;
     }
     /**
      * The list pos specifies which parameter to use in the list
      * ParameterSettings::list.
      */
     void setListPos(int pos)
     {
         m_listPos = pos;
     }
     /**
      * \see setSliderID
      */
     int sliderID() const
     {
         return m_sliderID;
     }
     /**
      * \see setListPos
      */
     int listPos() const
     {
         return m_listPos;
     }
     /**
      * \return Whether the parameter referred to is the same.
      */
     bool operator==(const Parameter &other) const;
 
 protected:
     Type m_type;
     int m_sliderID;
     int m_listPos;
 };
 
 /** Here are all attributes for a function. */
 class Function
 {
 public:
     enum PMode {
         Derivative0,
         Derivative1,
         Derivative2,
         Derivative3,
         Integral,
     };
 
     enum Type {
         Cartesian,
         Parametric,
         Polar,
         Implicit,
         Differential,
     };
 
     explicit Function(Type type);
     ~Function();
 
     /**
      * \return the type of function.
      */
     Type type() const
     {
         return m_type;
     }
 
     enum PlotCombination {
         DifferentParameters = 0x1, ///< For all the different parameters
         DifferentDerivatives = 0x2, ///< Derivatives of the function
         DifferentPMSignatures = 0x4, ///< Plus-minus combinations
         DifferentInitialStates = 0x8, ///< For differential equations; different states
         AllCombinations = 0x20 - 1
     };
     typedef QFlags<PlotCombination> PlotCombinations;
 
     /**
      * \return a list of plots for this function,
      */
     QList<Plot> plots(PlotCombinations combinations = AllCombinations) const;
     /**
      * \return A string for displaying to the user that identifies this
      * function. For identifying plots uniquely, see Plot::name()
      */
     QString name() const;
     /**
      * Converts the type to a string (which is used in save files).
      */
     static QString typeToString(Type type);
     /**
      * Converts the string to a type (used when loading files).
      */
     static Type stringToType(const QString &type);
     /**
      * Sets the current working parameter (which is used in calculations).
      */
     void setParameter(double p)
     {
         k = p;
     }
     /**
      * The function parameter, as set by e.g. a slider.
      */
     double k;
     /**
      * Clears the list of functions that this function depends on.
      */
     void clearFunctionDependencies()
     {
         m_dependencies.clear();
     }
     /**
      * Adds \p function to the list of functions that this function depends
      * on. For example, if this function is "f(x) = 1 + g(x)", then this
      * function depends on the function g(x).
      */
     void addFunctionDependency(Function *function);
     /**
      * \return whether this function or any of the functions that this
      * function depend on, etc, depend on \p function.
      */
     bool dependsOn(Function *function) const;
     /**
      * Copies data members across, while avoiding id, mem, mptr type
      * variables.
      * @return whether any values have changed.
      */
     bool copyFrom(const Function &function);
     /**
      * \return the function ID, used to identify it from the parser.
      */
     uint id() const
     {
         return m_id;
     }
     /**
      * \see id()
      */
     void setId(uint id)
     {
         m_id = id;
     }
     QVector<Equation *> eq;
     /**
      * \return A reference to the appearance of the given plot type.
      */
     PlotAppearance &plotAppearance(PMode plot);
     /**
      * \return The appearance of the given plot type.
      */
     PlotAppearance plotAppearance(PMode plot) const;
     /**
      * \returns true if all plots are hidden (i.e. plotAppearance().visible
      * is false for all plot types).
      * \returns false otherwise.
      */
     bool allPlotsAreHidden() const;
     /**
      * Custom plot range, lower boundary.
      */
     Value dmin;
     /**
      * Custom plot range, upper boundary.
      */
     Value dmax;
 
     ParameterSettings m_parameters;
 
     bool usecustomxmin : 1;
     bool usecustomxmax : 1;
     // TODO double slider_min, slider_max; ///< extreme values of the slider
 
     /**
      * For use with implicit functions, when either x or y is held fixed.
      */
     enum ImplicitMode {
         FixedX,
         FixedY,
         UnfixedXY,
 
     };
     ImplicitMode m_implicitMode;
     /**
      * The value of x when this is an implicit function and x is fixed.
      */
     double x;
     /**
      * The value of y when this is an implicit function and y is fixed.
      */
     double y;
 
     /**
      * A list with all functions that this function depends on.
      */
     QList<int> m_dependencies;
 
 protected:
     uint m_id;
     const Type m_type;
 
     PlotAppearance f0; ///< The actual function - the "zero'th derivative"
     PlotAppearance f1; ///< First derivative
     PlotAppearance f2; ///< Second derivative
     PlotAppearance f3; ///< Third derivative
     PlotAppearance integral; ///< integral
 };
 
 /**
  * Uniquely identifies a single plot (i.e. a single curvy line in the View).
  */
 class Plot
 {
 public:
     Plot();
 
     bool operator==(const Plot &other) const;
 
     void setFunctionID(int id);
     /**
      * Changes the plotMode equivalent to differentiating.
      */
     void differentiate();
     /**
      * Changes the plotMode equivalent to integrating.
      */
     void integrate();
     int functionID() const
     {
         return m_functionID;
     }
     /**
      * \return a pointer to the function with ID as set by setFunctionID
      */
     Function *function() const
     {
         return m_function;
     }
     /**
      * \return the value of the parameter associated with this plot.
      */
     double parameterValue() const;
     /**
      * Generates a name appropriate for distinguishing the plot from others.
      */
     QString name() const;
     /**
      * The color that the plot should be drawn with.
      */
     QColor color() const;
     /**
      * Parameter in use.
      */
     Parameter parameter;
     /**
      * Which derivative.
      */
     Function::PMode plotMode;
     /**
      * Converts the plotMode to the derivative number, e.g.
      * Function::Derivative1 -> 1, and Function::Integral -> -1
      */
     int derivativeNumber() const;
     /**
      * Assigned when Function::allPlots() is called. The plots for each
      * plotMode are numbered 0 to *.
      */
     int plotNumber;
     /**
      * The total number of plots of the same plotMode as this.
      */
     int plotNumberCount;
     /**
      * Updates the current working parameter value in the function that
      * this plot is for and the plus-minus signature for the function's
      * equations.
      */
     void updateFunction() const;
     /**
      * For differential equations, which state to draw. It's probably
      * easier to use the function differentialState(), however.
      */
     int stateNumber;
     /**
      * \return the differential state for the plot (or 0 if no state).
      */
     DifferentialState *state() const;
     /**
      * For equations containing a plus-minus symbols, this indicates
      * whether to take the plus or the minus for each one. The list is for
      * each equation of the function (so typically, the list will only be
      * of size one, but parametric functions will have two).
      */
     QList<QVector<bool>> pmSignature;
 
 protected:
     void updateCached();
 
     int m_functionID; ///< ID of function
     Function *m_function; ///< Cached pointer to function
 };
 
 #endif // FUNCTION_H