JKQTPlotter trunk/v5.0.0
an extensive Qt5+Qt6 Plotter framework (including a feature-richt plotter widget, a speed-optimized, but limited variant and a LaTeX equation renderer!), written fully in C/C++ and without external dependencies
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Example (JKQTPlotter): Plotting Parametric Mathematical Curves as Line Graphs

Basics

This project (see ./examples/evalcurve/) demonstrates how to plot mathematical functions as line graphs with JKQTPXYFunctionLineGraph. The functions may be defined as static C functions, C++ functors or c++ inline functions. The functions may simply depend on the parameter t, or on t and a vector of parameters.

The class uses an adaptive algorithm, which determines by the local slope, at how many points (or how close points) the functor has to be evaluated.

If you want to evaluate the parametric function explicitly, you can use JKQTPXYLineGraph or JKQTPXYParametrizedScatterGraph and have a look at the example ./examples/parametriccurve.

Simple C++ inline function

The example shows how to plot a simple C++ inline function:

func1->setPlotFunctionFunctor([](double t) ->QPointF {
return QPointF(
sin(t)*(exp(cos(t))-2.0*cos(4.0*t)-jkqtp_pow5(sin(t/12.0))),
cos(t)*(exp(cos(t))-2.0*cos(4.0*t)-jkqtp_pow5(sin(t/12.0)))
);
});
func1->setTRange(0, 12.0*JKQTPSTATISTICS_PI);
func1->setTitle("C++-inline function: \"Butterfly Curve\"");
plot->addGraph(func1);
virtual void setTitle(const QString &__value)
sets the title of the plot (for display in key!).
void setTRange(double tmin_, double tmax_)
set the t-value range for
This implements line plots where the data is taken from a user supplied function The function is eva...
Definition jkqtpevaluatedparametriccurve.h:172
void setPlotFunctionFunctor(jkqtpParametricCurveFunctionType &&__value)
sets a functor to be plotted
T jkqtp_pow5(T x)
5-th power of a number
Definition jkqtpmathtools.h:347
#define JKQTPSTATISTICS_PI
Definition jkqtpmathtools.h:52

Note that here a functor is defined, which calculates the points on a Butterfly Curve, i.e. a function mapping a parameter t to a two-dimensional point QPointF with complex functions for x and y. This function is evaluated on a range of values for t, set by

Simple C++ inline function with Parameters

JKQTPXYFunctionLineGraph allows to use more complex functors alternatively: These depend on the variable tand a vector of parameters. Here is an example:

func2->setPlotFunctionFunctor([](double t, const QVector<double>& params) ->QPointF {
return QPointF(
3.0*sin(params[0]*t+params[2])+8.0,
3.0*sin(params[1]*t)
);
});
// now we define the 3 parameters of the function
func2->setParamsV(5, 4, JKQTPSTATISTICS_PI/4.0);
// and define the range over which to evaluate
func2->setTRange(0, 2.0*JKQTPSTATISTICS_PI);
func1->setTitle("C++-inline function $[ sin(5{\\cdot}t+\\pi/4), sin(4{\\cdot}t) ]$");
plot->addGraph(func1);

In the functor we can use the entries in the vector param as function parameters. The values in this vector are defined by

// now we define the 3 parameters of the function
func2->setParamsV(5, 4, JKQTPSTATISTICS_PI/4.0);

Alternatively they can also be taken from a column in the internal datastore. Then you have to call:

func2->setParameterColumn(ColumnID);

instead, where ColumnID is the ID of the column with the parameter values.

Screenshot

This code snippets above result in a plot like this:

evalcurve

Notes

This example describes how to draw 2D parametric curves. For (simpler) 1D-functions f(x) or f(y), see examples/functionplot .