Chris Taylor
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 Oct16 comment Integrate by parts: $\int x\,\tan^2(2x) dx$ What are $t$ and $g$? Is it one function $tg$? Or are they constants? Oct4 revised Choice Problem: choose 5 days in a month, consecutive days are forbidden added 17 characters in body Oct4 comment Choice Problem: choose 5 days in a month, consecutive days are forbidden Thanks, edited :) Oct4 answered Choice Problem: choose 5 days in a month, consecutive days are forbidden Oct1 awarded Good Question Sep30 awarded Explainer Sep28 revised How do you integrate imaginary numbers? added 15 characters in body Sep26 comment Consider the problem minimize $f(x)= x^4 −1.$ The proof of quadratic convergence for Newton's method uses the fact that the first derivative of the function whose zero you are finding (i.e. $f''(x)$ in your case) does not vanish on some interval surrounding the root. But you have $f''(x) = 12x^2$ which is zero at the root $x=0$, so the proof of quadratic convergence fails. Sep26 comment Solve linear system with matlab Also, your text specifies $m\geq n$ but your example has $m < n$ (although I don't think this is relevant - probably just a typo). Sep26 comment Solve linear system with matlab You have more equations than unknowns; why do you expect to be able to find an exact solution? Sep11 comment Pseudo Proofs that are intuitively reasonable @MJD Yes, good to mention the Andreas Blass paper too. I'm not sure whether I knew about it or not when I wrote this answer. If I did, then it was surely an oversight. Sep11 awarded Nice Answer Sep10 awarded Nice Answer Sep10 revised Why do we use a Least Squares fit? deleted 116 characters in body Aug7 comment Coordinate descent with constraints Thanks Michael! Aug7 accepted Coordinate descent with constraints Aug6 comment Coordinate descent with constraints Thanks for this answer Michael. Is it easy to see that when dealing with coordinate-wise bounds, thresholding to $l_i\leq x_i\leq u_i$ at each step results in the global minimizer for the problem I posed (convex function with separable non-smooth constraints and coordinate-wise bounds)? Aug5 asked Coordinate descent with constraints Aug1 comment What are some conceptualizations that work in mathematics but are not strictly true? @BCLC a physicist would say $f(r,\theta)=r^2$ whereas a mathematician would say $f(r,\theta)=r^2+\theta^2$. Jul29 awarded Good Answer