Tom-Alexander/regression-js

X intercept?

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Tzikas commented

How do I predict the x intercept of a polynomial or exponential function?

I have data with Date.now() and percentage values like so [[1515569440034,1],[1515569456654,0.8333333333333334],[1515569522244,0.16666666666666666],[1515569563911,0.16666666666666666],[1515569594707,0.16666666666666666],[1515569628485,0.16666666666666666],[1515569637613,0.6666666666666666],[1515569657209,0.16666666666666666],[1515569745083,0.16666666666666666]] and I'm trying to find the Date when the percentage will equal zero. The prediction function seems to return the y value but I'm looking for the x. Am I missing something obvious?

Also do I need to normalize the numbers because one is so large and the other is so small?

Tom-Alexander commented

You could use the model coefficients to solve for y = 0. Depending on your data set, the bisection method may be appropriate. https://en.wikipedia.org/wiki/Root-finding_algorithm