C#

double[] known_Ys, new_Ys, known_Xs, new_Xs;
   // Both of the known arrays have a length of 7
   // The new arrays have a length of 5
   // All arrays were loaded with valid double values
   // except new_Ys which will contain the result
Excel.WorksheetFunction wsf = Application.WorksheetFunction;
object results = wsf.Growth(known_Ys, known_Xs, new_Xs, System.Type.Missing);

System.Array resultsArray = results as System.Array;
if (resultsArray != null)
{
   int idx = resultsArray.GetLowerBound(0);
   for (int i = 0; i < new_Ys.Length; i++)
   {
      new_Ys[i] = (double)resultsArray.GetValue(idx);
      idx++;
   }
   return new_Ys;
}
else
{
   // Handle exception.
   return null;
}

Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

Protected Sub OnPropertyChanged(ByVal strPropertyName As String)
  If Me.PropertyChangedEvent IsNot Nothing Then
    RaiseEvent PropertyChanged(Me, New System.ComponentModel.PropertyChangedEventArgs(strPropertyName))
  End If
End Sub