title: How does jqplot calculate bar width?
body: <p>I'm trying to understand how jqplot calculates the width of bars when the width is not specified. Say I have the following chart:</p>
  
  <pre><code>$.jqplot(chartDiv.attr("id"), [
      [
          ['2013-02-15', 0],
          ['2013-03-01', 2],
          ['2013-03-15', 4],
          ['2013-03-29', 6],
          ['2013-04-12', 8],
          ['2013-04-26', 10],
          ['2013-05-10', 12],
          ['2013-05-24', 14],
          ['2013-06-07', 16],
          ['2013-06-21', 18],
          ['2013-07-05', 20],
          ['2013-07-19', 22],
          ['2013-08-02', 24],
          ['2013-08-16', 26],
          ['2013-08-30', 28],
          ['2013-09-13', 30],
          ['2013-09-27', 32],
          ['2013-10-11', 34],
          ['2013-10-25', 36],
          ['2013-11-08', 38], , ], ], {
  
  
      axes: {
          xaxis: {
              renderer: $.jqplot.DateAxisRenderer,
              min: '2013-1-20',
              max: '2013-12-1',
              tickRenderer: $.jqplot.CanvasAxisTickRenderer,
              tickInterval: '14 days',
              tickOptions: {
                  angle: 45,
                  formatString: '%d/%m/%Y',
              },
          }
      },
      series: [{
          xaxis: 'xaxis',
          yaxis: 'yaxis',
          renderer: $.jqplot.BarRenderer,
      }],
      seriesDefaults: {
          shadow: false,
      },
      axesDefaults: {
         useSeriesColor: true,
          rendererOptions: {
              alignTicks: true
          }
      },
  });
  </code></pre>
  
  <p>When I change tickInterval between 7 days and 14 days, the width of the bars alters, despite there being the same number of bars on the same physical area. How is tickInterval used in the calculation of bar widths? Or failing that, how can I alter this example such that tickInterval can vary (it will be calculated from data eventually) but the width of the bars be set to something sensible?</p>