- double display_units = ceil(log10(units)/2.0);
- setAxisScale(QwtPlot::xBottom, _startFrequency, _stopFrequency);
- setAxisScaleDraw(QwtPlot::xBottom, new FreqDisplayScaleDraw(display_units));
- setAxisTitle(QwtPlot::xBottom, QString("Frequency (%1)").arg(strunits.c_str()));
- ((FreqDisplayZoomer*)_zoomer)->SetFrequencyPrecision(display_units);
- ((FreqDisplayZoomer*)_zoomer)->SetUnitType(strunits);
+ if(stopFreq > startFreq) {
+ _startFrequency = startFreq;
+ _stopFrequency = stopFreq;
+
+ if((axisScaleDraw(QwtPlot::xBottom) != NULL) && (_zoomer != NULL)){
+ double display_units = ceil(log10(units)/2.0);
+ setAxisScaleDraw(QwtPlot::xBottom, new FreqDisplayScaleDraw(display_units));
+ setAxisTitle(QwtPlot::xBottom, QString("Frequency (%1)").arg(strunits.c_str()));