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Custom Excel Trendline

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BenzoX -  
piopicolo Posted messages 1422 Status Member -
Hello,

I would like to know how, in Excel, to determine the equation of a curve when knowing its form: I have a series of points, and I would like to model it by P0(2 - exp(-kt)), with k unknown; and I think there is a way less tedious than converting to an exponential form to directly use the "trendline" tool.

Thank you in advance,
BenzoX

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1 answer

  1.
    piopicolo Posted messages 1422 Status Member 200
     
    yet it's the simplest
    otherwise, one needs to solve several equations by looking for values if they are known for x=0 and x=infinity

    A+
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    1. BenzoX
       
      Alright, I thought Excel would make it easier for us by solving the equations for each value of t given to it, and then averaging the solutions.
      In any case, it seems my model is not good; the correlation coefficient is really low.
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    2. piopicolo Posted messages 1422 Status Member 200
       
      You can create a trend line by including values incrementally.
      You can start with a curve based on three points, then four, and so on. In this case, the curves are accurate as they are calculated from the points and not averaged.
      Exponential curves are easy to find. By taking the logarithm, we get a straight line!
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