check qwt-5.2, r588 into repository

2026-02-14 16:39:57 +00:00 · 2009-09-20 10:09:15 -07:00
parent cc7710b2c7
commit 44b602d775
279 changed files with 57199 additions and 0 deletions
--- a/qwt/examples/bode/bode_plot.cpp
+++ b/qwt/examples/bode/bode_plot.cpp
@@ -0,0 +1,181 @@
+#include <qwt_math.h>
+#include <qwt_scale_engine.h>
+#include <qwt_symbol.h>
+#include <qwt_plot_grid.h>
+#include <qwt_plot_marker.h>
+#include <qwt_plot_curve.h>
+#include <qwt_legend.h>
+#include <qwt_text.h>
+#include "cplx.h"
+#include "bode_plot.h"
+
+static void logSpace(double *array, int size, double xmin, double xmax)
+{ 
+    if ((xmin <= 0.0) || (xmax <= 0.0) || (size <= 0))
+       return;
+
+    const int imax = size -1;
+
+    array[0] = xmin;
+    array[imax] = xmax;
+
+    const double lxmin = log(xmin);
+    const double lxmax = log(xmax);
+    const double lstep = (lxmax - lxmin) / double(imax);
+
+    for (int i = 1; i < imax; i++)
+       array[i] = exp(lxmin + double(i) * lstep);
+}
+
+BodePlot::BodePlot(QWidget *parent):
+    QwtPlot(parent)
+{
+    setAutoReplot(false);
+
+    setTitle("Frequency Response of a Second-Order System");
+
+    setCanvasBackground(QColor(Qt::darkBlue));
+
+    // legend
+    QwtLegend *legend = new QwtLegend;
+    legend->setFrameStyle(QFrame::Box|QFrame::Sunken);
+    insertLegend(legend, QwtPlot::BottomLegend);
+
+    // grid 
+    QwtPlotGrid *grid = new QwtPlotGrid;
+    grid->enableXMin(true);
+    grid->setMajPen(QPen(Qt::white, 0, Qt::DotLine));
+    grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
+    grid->attach(this);
+
+    // axes
+    enableAxis(QwtPlot::yRight);
+    setAxisTitle(QwtPlot::xBottom, "Normalized Frequency");
+    setAxisTitle(QwtPlot::yLeft, "Amplitude [dB]");
+    setAxisTitle(QwtPlot::yRight, "Phase [deg]");
+
+    setAxisMaxMajor(QwtPlot::xBottom, 6);
+    setAxisMaxMinor(QwtPlot::xBottom, 10);
+    setAxisScaleEngine(QwtPlot::xBottom, new QwtLog10ScaleEngine);
+  
+    // curves
+    d_crv1 = new QwtPlotCurve("Amplitude");
+#if QT_VERSION >= 0x040000
+    d_crv1->setRenderHint(QwtPlotItem::RenderAntialiased);
+#endif
+    d_crv1->setPen(QPen(Qt::yellow));
+    d_crv1->setYAxis(QwtPlot::yLeft);
+    d_crv1->attach(this);
+
+    d_crv2 = new QwtPlotCurve("Phase");
+#if QT_VERSION >= 0x040000
+    d_crv2->setRenderHint(QwtPlotItem::RenderAntialiased);
+#endif
+    d_crv2->setPen(QPen(Qt::cyan));
+    d_crv2->setYAxis(QwtPlot::yRight);
+    d_crv2->attach(this);
+    
+    // marker
+    d_mrk1 = new QwtPlotMarker();
+    d_mrk1->setValue(0.0, 0.0);
+    d_mrk1->setLineStyle(QwtPlotMarker::VLine);
+    d_mrk1->setLabelAlignment(Qt::AlignRight | Qt::AlignBottom);
+    d_mrk1->setLinePen(QPen(Qt::green, 0, Qt::DashDotLine));
+    d_mrk1->attach(this);
+
+    d_mrk2 = new QwtPlotMarker();
+    d_mrk2->setLineStyle(QwtPlotMarker::HLine);
+    d_mrk2->setLabelAlignment(Qt::AlignRight | Qt::AlignBottom);
+    d_mrk2->setLinePen(QPen(QColor(200,150,0), 0, Qt::DashDotLine));
+    d_mrk2->setSymbol( QwtSymbol(QwtSymbol::Diamond, 
+        QColor(Qt::yellow), QColor(Qt::green), QSize(7,7)));
+    d_mrk2->attach(this);
+
+    setDamp(0.0);
+
+    setAutoReplot(true);
+}
+
+void BodePlot::showData(double *frequency, double *amplitude,
+    double *phase, int count)
+{
+    d_crv1->setData(frequency, amplitude, count);
+    d_crv2->setData(frequency, phase, count);
+}
+
+void BodePlot::showPeak(double freq, double amplitude)
+{
+    QString label;
+    label.sprintf("Peak: %.3g dB", amplitude);
+
+    QwtText text(label);
+    text.setFont(QFont("Helvetica", 10, QFont::Bold));
+    text.setColor(QColor(200,150,0));
+
+    d_mrk2->setValue(freq, amplitude);
+    d_mrk2->setLabel(text);
+}
+
+void BodePlot::show3dB(double freq)
+{
+    QString label;
+    label.sprintf("-3 dB at f = %.3g", freq);
+
+    QwtText text(label);
+    text.setFont(QFont("Helvetica", 10, QFont::Bold));
+    text.setColor(Qt::green);
+
+    d_mrk1->setValue(freq, 0.0);
+    d_mrk1->setLabel(text);
+}
+
+//
+// re-calculate frequency response
+//
+void BodePlot::setDamp(double damping)
+{
+    const bool doReplot = autoReplot();
+    setAutoReplot(false);
+
+    const int ArraySize = 200;
+
+    double frequency[ArraySize];
+    double amplitude[ArraySize];
+    double phase[ArraySize];
+
+    // build frequency vector with logarithmic division
+    logSpace(frequency, ArraySize, 0.01, 100);
+
+    int i3 = 1;
+    double fmax = 1;
+    double amax = -1000.0;
+    
+    for (int i = 0; i < ArraySize; i++)
+    {
+        double f = frequency[i];
+        cplx g = cplx(1.0) / cplx(1.0 - f * f, 2.0 * damping * f);
+        amplitude[i] = 20.0 * log10(sqrt( g.real()*g.real() + g.imag()*g.imag()));
+        phase[i] = atan2(g.imag(), g.real()) * (180.0 / M_PI);
+
+        if ((i3 <= 1) && (amplitude[i] < -3.0)) 
+           i3 = i;
+        if (amplitude[i] > amax)
+        {
+            amax = amplitude[i];
+            fmax = frequency[i];
+        }
+        
+    }
+    
+    double f3 = frequency[i3] - 
+       (frequency[i3] - frequency[i3 - 1]) 
+          / (amplitude[i3] - amplitude[i3 -1]) * (amplitude[i3] + 3);
+    
+    showPeak(fmax, amax);
+    show3dB(f3);
+    showData(frequency, amplitude, phase, ArraySize);
+
+    setAutoReplot(doReplot);
+
+    replot();
+}