title: Making an NSDecimal for CorePlot
body: <p>I have a coreplot item y.majorIntervalLength which I believe to be of type NSDecimal.  I need to fill it with a value that I calculate from a couple of doubles.  The problem is when I go to assign the resulting double to y.majorIntervalLength I get:</p>
  
  <p>Incompatible type for Argument 1...</p>
  
  <p>I do not know how to convert a value from a double to an NSDecimal which is what I gather is required for the y.majorIntervalLength.  </p>
  
  <p>How do I package/wrap/cast  this value to the correct format?</p>
  
  <p>What do I need to read to learn this kind of thing?</p>
  
  <p>Thanks</p>