TASK
How to get the r-squared value or a trend line.
SOLUTION 
The statistical engine can be used to calculate this value.
Getting the r-squared value of a trend line.
The r-squared value of mySeries will be stored int r2. 
| [C#] 
 double r2 = StatisticalEngine.CorrelationCoefDeterminantion("",mySeries).YValue;    | 
  
| [Visual Basic] 
 Dim r2 As Double = StatisticalEngine.CorrelationCoefDeterminantion("",mySeries).YValue    |