JKQtPlotter/test/jkqtplotter_simpletest_logaxes/jkqtplotter_simpletest_logaxes.cpp

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2018-11-30 05:48:31 +08:00
#include <QApplication>
#include "jkqtplotter/jkqtplotter.h"
#include "jkqtplotter/jkqtpgeoelements.h"
#include "jkqtplottertools/jkqtptools.h"
#define sqr(x) ((x)*(x))
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
// 1. create a plotter window and get a pointer to the internal datastore (for convenience)
JKQtPlotter plot;
JKQTPdatastore* ds=plot.getDatastore();
// 2. now we create data a vector of x-values for a simple plot (resonance curve with different damping value D)
// see https://en.wikipedia.org/wiki/Resonance
QVector<double> X;
QVector<double> D { 0.001, 0.1, 1, 10};
const int Ndata=500; // number of plot points in each curve
for (int i=0; i<Ndata; i++) {
const double x=double(i)/double(Ndata)*3;
X<<x;
//Y1<<1.0/sqrt(sqr(1-sqr(x))+sqr(2*x*D1));
}
// and copy it to the datastore
size_t columnX=ds->addCopiedColumn(X, "x");
// 3. now we make several plots for different values of D
QVector<Qt::PenStyle> pens {Qt::SolidLine, Qt::DashLine, Qt::DotLine, Qt::DashDotLine, Qt::DashDotDotLine };
for (int id=0; id<D.size(); id++) {
// generate some plot data
QVector<double> Y;
for (auto& xx: X) {
Y<<1.0/sqrt(sqr(1-sqr(xx))+sqr(2*xx*D[id]));
}
JKQTPxyLineGraph* graph=new JKQTPxyLineGraph(&plot);
// copy data into datastore and immediately set the yColumn
graph->set_xColumn(columnX);
graph->set_yColumn(ds->addCopiedColumn(Y, "y"+QString::number(id)));
// don't use symbols
graph->set_symbol(JKQTPnoSymbol);
// use one of different pens
graph->set_style(pens[id%pens.size()]);
// set width of graph line
graph->set_lineWidth(1.5);
// graph title is made from symbol+penstyle
graph->set_title(QString("D=\\delta/\\omega_0=%1").arg(D[id]));
// add the graph to the plot, so it is actually displayed
plot.addGraph(graph);
}
// 4. Also we add a text-element in the plot to show the plotted function
// This element (JKQTPgeoText) is taken from the set of geometric elements
// and is simply parametrized by a position (1.25/10) and the text to display.
// In addition you can also set the font size (here to 15)
plot.addGraph(new JKQTPgeoText(&plot, 1.25, 10, "\\frac{A}{A_{stat}}=\\frac{1}{\\sqrt{\\left(1-\\eta^2\\right)^2+\\left(2{\\eta}D\\right)^2}}", 15));
// for nicer rendering we set the fonts used by the internal LaTeX parser instance to XITS
//plot.get_plotter()->get_mathText()->useXITS();
// 4. set y-axis to logarithmic (x-axis would be analogous)
// and set axis labels (using LaTeX notation)
plot.get_yAxis()->set_logAxis(true);
plot.get_yAxis()->set_axisLabel("Amplitude A/A_{stat}");
plot.get_xAxis()->set_axisLabel("relative driving frequency \\eta=\\omega/\\omega_0");
// 5. autoscale the plot so the graph is contained
plot.zoomToFit();
// 6. show plotter and make it a decent size
plot.show();
plot.resize(600,400);
return app.exec();
}