The exponential fit in Excel isn't really doing what I want it to do (the fitted exponential is clearly upside-down in the first graph) and I was wondering if there was an easy way to fix this or an explanation as to why it won't fit it the way I would like it to.

I had a quick fix which involved transforming the data (the second graph).

Graphs and data

  • "negative exponential" is called log:) Apr 25, 2017 at 16:53
  • @MátéJuhász ln(x) is the inverse of e^x. What I am talking about is something like -e^(-x)
    – Curtis
    Apr 25, 2017 at 17:07
  • You can use Excel solver to fit, say, y=a-b*exp(c*x) to the data.
    – g.kov
    Apr 25, 2017 at 17:15
  • 1
    The log fits perfectly your data Apr 25, 2017 at 17:18
  • @fernando.reyes that's not the method of fit that I want though, seeing as it is a first order system, I know that it should be an exponential not a logarithm.
    – Curtis
    Apr 25, 2017 at 17:24


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