User talk:217.155.99.99

thanks for fixing the variable name at Lagrange polynomial
Hi 217.155.99.99, and welcome to Wikipedia. Thanks for fixing the typo in the variable name at Lagrange polynomial. I rewrote that section of the article by copy/pasted some formulas from some of my own notes about the Barycentric formula (in a complex variable context) and missed changing one of the zs to xs. –jacobolus (t) 11:46, 4 July 2022 (UTC)
 * And whoops, thanks for also fixing that index mixup. If we define $\ell_j(x) = \prod_{m\neq j} (x-x_m)(x_j-x_m)^{-1}$ and $\ell_j(x) = \ell(x) w_j(x - x_j)^{-1}$  then makes more sense to follow-up with $w_j = \prod_{m\neq j}(x_j - x_m)^{-1}$  rather than the potentially sign-reversed $w_j = \prod_{m\neq j}(x_m - x_j)^{-1}$  (though flipping the sign makes no practical difference, still defining the same interpolating polynomial). I think that mistake slipped in because the Wikipedia article uses funny variable names for indices, and I also had to swap all the indices in my copy/pasting. –jacobolus (t) 13:07, 4 July 2022 (UTC)
 * By the way, if you are working with barycentric Lagrange polynomials, you may enjoy playing with this interactive Desmos chart, https://www.desmos.com/calculator/qijzjcpi4a –jacobolus (t) 13:38, 4 July 2022 (UTC)

Hi - this is me, I forgot to log in. Not to worry - I was referring to the article while doing some formal verification work, and my proofs weren't formally verifying! --LinesInk (talk) 14:26, 4 July 2022 (UTC)