userdefined trendline

[Guest]

I need constract trendline with equation y=a1*EXP(a2/(x-a3))+a4 using Excel.
(a1..a4 are to define)
Could you please advise me how one can do it?
Thanks a lot.

 

[Andy Pope]

Hi,

Have a look at this,
http://www.tushar-mehta.com/excel/software/plot_manager/index.html

Cheers
Andy

 

[Jerry W. Lewis]

Andy Pope has covered the plotting of the function. By "(a1..a4 are to
define)" you mean that you also want to know how to fit the coefficients?

If so, suppose that cells A1:A4 are used to hold trial values for
a1..a4. Array enter (Ctrl-Shift-Enter) the following formula
=SUM((yData-(A1*EXP(A2/(x-A3))+A4))^2)
and use Solver to minimize that formula by changing cells A1:A4.

Jerry

 

[Guest]

Thank you very much!
Work without problems.

 

[Jerry W. Lewis]

You are welcome. Glad it helped.

Jerry