# How to find equation when i have points?

I have points and need to get equation of these points. I try to use wolfram and another online services and all result is bad.

You could use Polynomials.jl to fit a polynomial in the y-axis variable.

For a 4th-order polynomial, this gives:

2 Likes

Thank you very much!
Can you share code? I don’t know how to convert data from `.mat` to `.jl`. I can convert to numpy array and then to `.jl`, but it long

Sorry, I did this in the REPL and the code is a mess to cut and paste.

To read the Matlab files, I have used the MAT.jl package.

What am i doing wrong?

``````f4 = fit(I0_data, U0_data, 4)
-725636.891507482 - 1.9486539668049992e6∙x - 1.9622241946502575e6∙x^2 - 878106.3537953914∙x^3 - 147347.79216010476∙x^4
``````
``````function equat(x)
-725636.891507482 .- 1.9486539668049992e6*x .- 1.9622241946502575e6*x.^2 - 878106.3537953914*x.^3 .- 147347.79216010476*x.^4
end

ytest = equat(I0_data);
``````

I think you need to switch between `I0_data` and `U0_data` as the arguments usally go x = p(y) and you want to fit polynomial over y input value with x output value.

It helped, thank you!