title: d3js time scale same value but different results
body: <p>I have two overlapping charts. One is a barchart and one is a linechart.
  Both have in each data a date (the same date - same count of results) But if I calculate the attr x for each chart I get different results.</p>
  
  <pre><code>var x = d3.time.scale().range([0, width]);
  </code></pre>
  
  <p>width = 860.
  So I debugged very deep in d3js-code and recognized the following:</p>
  
  <p>If I call x (x(d.value) and step into it I came to the following code:</p>
  
  <pre><code>    function d3_uninterpolateNumber(a, b) {
  b = b - (a = +a) ? 1 / (b - a) : 0;
  return function(x) {
    return (x - a) * b;
  };
    }
  </code></pre>
  
  <p>I saw that <b>x</b> and <b>a</b> have the same value (x is a date (Tue Jul 2 00:00:00 UTC+0200 2013) and a are ticks (1372716000000 --> the ticks of the first date in my data) in case of 2nd of July. </p>
  
  <p>But b has different values. So I have no idea what b is.
  In case of barchart it is 3.7947783849423196e-10 and in case of LineChart it's 3.7947783849423196e-10
  So the result of x(d.value) is different, but it shouldn't be. </p>
  
  <p>Has anybody an idea?
  I try to get a fiddle tomorrow, but maybe somebody has the answer without js-fiddle.</p>
  
  <p>thx in advance
  ©a-x-i</p>