How do I calculate the inflection point?
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How do I calculate the inflection point?
I found a way to do it long hand (so to speak). I was hoping that excel had
a function that would just take the data plot a derivative curve for me from which I could pick out the maximum. Do you know of any way to do this that doesn't involve curve fitting? This is for a pH titration curve. Thanks for your help. "Gary''s Student" wrote: The curve in Excel is just a sequence of data points. Fit a curve to the data (mathematically expression). Take the 2nd derivatiove of the curve and look for points where the 2nd derivative goes thru zero while switching signs. -- Gary''s Student "rgoyan" wrote: I am trying to calculate the first derivative of a curve in excel to determine the inflection point. I know how to do this in Sigmaplot, but my students only have access to excel. Please reply to |
How do I calculate the inflection point?
Estimating the first derivative is not diffiuclt. Let's say the x's are in
column A and the y's are in column B. In C2 enter: =(B3-B1)/(A3-A1) and copy down the column. This is an estimate of dy/dx at the point [A2,B2]. In a similar fashion you can estimate the second derivative in column D. -- Gary's Student "rgoyan" wrote: I found a way to do it long hand (so to speak). I was hoping that excel had a function that would just take the data plot a derivative curve for me from which I could pick out the maximum. Do you know of any way to do this that doesn't involve curve fitting? This is for a pH titration curve. Thanks for your help. "Gary''s Student" wrote: The curve in Excel is just a sequence of data points. Fit a curve to the data (mathematically expression). Take the 2nd derivatiove of the curve and look for points where the 2nd derivative goes thru zero while switching signs. -- Gary''s Student "rgoyan" wrote: I am trying to calculate the first derivative of a curve in excel to determine the inflection point. I know how to do this in Sigmaplot, but my students only have access to excel. Please reply to |
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