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#1
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How do I get the gradient at a point on a curved graph?
I have a plot of experimental data and I inserted an exponential trendline
that fits the data very well. I'd like to "differentiate" the curve as I need its gradient at certain points; as in I need Excel to draw the tangent to the trendline at a given point and tell me its equation. Can anyone help me do this? Thank you all so much. |
#2
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I don't think Excel knows how to do this as a built in thing. Extract the coefficients of the trendline to a worksheet (using a worksheet function such as LOGEST or a utility that will extract trendline coefficients to a worksheet). Then you can use the coefficients and your knowledge of calculus to determine a formula for the slope of the function at any point. Then use that formula to put together a series of data points that you can plot as the tangent of the curve. -- MrShorty ------------------------------------------------------------------------ MrShorty's Profile: http://www.excelforum.com/member.php...o&userid=22181 View this thread: http://www.excelforum.com/showthread...hreadid=468456 |
#3
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thanks loads, i'll try it out :)
"MrShorty" wrote: I don't think Excel knows how to do this as a built in thing. Extract the coefficients of the trendline to a worksheet (using a worksheet function such as LOGEST or a utility that will extract trendline coefficients to a worksheet). Then you can use the coefficients and your knowledge of calculus to determine a formula for the slope of the function at any point. Then use that formula to put together a series of data points that you can plot as the tangent of the curve. -- MrShorty ------------------------------------------------------------------------ MrShorty's Profile: http://www.excelforum.com/member.php...o&userid=22181 View this thread: http://www.excelforum.com/showthread...hreadid=468456 |
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