title: How can I make Bode plot working properly?
body: <p>I work on application for control engineering students. It can draw step and impulse plots, compute transfer function, check if object is stable etc. I want it to draw a Bode plot, and when I try to do it, I just can't set the <code>chart1.ChartAreas[0].AxisX.IsLogarithmic</code> property to <code>true</code>. It catches exceptions and the chart is badly red crossed.</p>
  
  <p>I suppose that this problem is caused by negative values - I plotted it in non-logarithmic scale and values varied from 0 to -200. Is there any way of making it work correctly?</p>
  
  <pre><code>      chart1.ChartAreas[0].AxisX.IsLogarithmic = false;
        var series1 = new System.Windows.Forms.DataVisualization.Charting.Series
        {
          ChartType = SeriesChartType.Line
        };
        this.chart1.ChartAreas[0].AxisX.Minimum = 1;
        this.chart1.Series.Add(series1);
        this.chart1.ResetAutoValues();
        for (double i = 1; i &lt; 10; i++) 
        {
          Complex y = TransferFunction.transmitancja_widmowa(i);
          double x = 20 * Math.Log10(y.Magnitude);
          MessageBox.Show(i.ToString());
          if (i &gt; 0)  series1.Points.AddXY(i, x);
        }
        chart1.ChartAreas[0].AxisX.IsLogarithmic = true;
        chart1.Invalidate();
  </code></pre>
  
  <p>Loop results:
      `1.1 : -3.44392273685111
  1.2 : -3.87389826338729
  1.3 : -4.29752280002408
  1.4 : -4.71291711058939
  1.5 : -5.11883360978875
  1.6 : -5.51449997972875
  1.7 : -5.89949601325708
  1.8 : -6.27365856592733
  1.9 : -6.63700925389649
  2 : -6.98970004336019
  2.1 : -7.3319726510657
  2.2 : -7.664128471124
  2.3 : -7.98650645445269
  2.4 : -8.29946695941636
  2.5 : -8.60338006570994
  2.6 : -8.89861721258189
  2.7 : -9.18554530550274
  2.8 : -9.46452265013073
  2.9 : -9.73589623427257
  3 : -10
  3.1 : -10.2571538390134
  3.2 : -10.5076631123304
  3.3 : -10.7518185461869
  3.4 : -10.9898963940118
  3.5 : -11.2221587827283
  3.6 : -11.4488541828714
  3.7 : -11.6702179579026
  3.8 : -11.8864729599972
  3.9 : -12.0978301484852
  4 : -12.3044892137827
  4.1 : -12.5066391946324
  4.2 : -12.7044590801796
  4.3 : -12.8981183911762
  4.4 : -13.0877777366472
  4.5 : -13.2735893438633
  4.6 : -13.4556975605639
  4.7 : -13.6342393291718
  4.8 : -13.809344633307
  4.9 : -13.981136917305
  5 : -14.1497334797082
  5.1 : -14.3152458418745
  5.2 : -14.4777800929462</p>
  
  <p>5.3 : -14.6374372124706
  5.4 : -14.7943133719774
  5.5 : -14.9485002168009
  5.6 : -15.1000851294023
  5.7 : -15.2491514753987
  5.8 : -15.3957788334531
  5.9 : -15.540043210119
  6 : -15.6820172406699
  6.1 : -15.8217703768841
  6.19999999999999 : -15.9593690626917
  6.29999999999999 : -16.0948768985328
  6.39999999999999 : -16.2283547952152
  6.49999999999999 : -16.3598611180083
  6.59999999999999 : -16.4894518216567
  6.69999999999999 : -16.6171805769466
  6.79999999999999 : -16.7430988894148
  6.89999999999999 : -16.8672562107454
  6.99999999999999 : -16.9897000433602
  7.09999999999999 : -17.1104760386703
  7.19999999999999 : -17.2296280894249
  7.29999999999999 : -17.3471984165568
  7.39999999999999 : -17.4632276508995
  7.49999999999999 : -17.5777549101192
  7.59999999999999 : -17.6908178711822
  7.69999999999999 : -17.8024528386535
  7.79999999999999 : -17.9126948091027
  7.89999999999999 : -18.0215775318696
  7.99999999999999 : -18.1291335664285
  8.09999999999999 : -18.2353943365686
  8.19999999999999 : -18.3403901815947
  8.29999999999999 : -18.4441504047382
  8.39999999999999 : -18.5467033189533
  8.49999999999999 : -18.6480762902615
  8.59999999999999 : -18.7482957787972
  8.69999999999999 : -18.8473873776963
  8.79999999999999 : -18.9453758499575
  8.89999999999999 : -19.0422851634008
  8.99999999999999 : -19.1381385238372
  9.09999999999999 : -19.232958406555
  9.19999999999999 : -19.326766586224
  9.29999999999998 : -19.4195841653081
  9.39999999999998 : -19.5114316010755
  9.49999999999998 : -19.6023287312851
  9.59999999999998 : -19.6922947986264
  9.69999999999998 : -19.7813484739829
  9.79999999999998 : -19.8695078785852
  9.89999999999998 : -19.9567906051162
  9.99999999999998 : -20.0432137378264`</p>