Can you please tell me what MS Excel uses to find a Power trendline? I have been experiment with data from my PunchBot project and it seems the Power Trendline fits the best. The plan is the used the data from my machine (an array of time intervals) to find the curve of the acceleration and used that to work out angular velocity and then torque. If you could tell me the maths that would great. If you could point me towards a library or some code (preferably c#) that would be superb. This links will hold some clues for those that can decifer... http://spreadsheetpage.com/index.php/tip/chart_trendline_formulas/ Many thanks!