Jason S
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 Jan 3 comment similarity transform mapping diagonal matrix of complex conjugates, to real matrix Oh. Huh, that seems too easy. Is there a way to express it directly in terms of $a$ and $b$? I figure it would help to express them in polar form as $a=r \cos \theta$ and $b = r \sin \theta$. Jan 3 asked similarity transform mapping diagonal matrix of complex conjugates, to real matrix Jan 1 comment Is there a faster algorithm than $O(n^2)$ for calculating “cofactors” $C_k = \prod\limits_{j\neq k}(c_k - c_j)$? could you elaborate? Jan 1 comment Is there a faster algorithm than $O(n^2)$ for calculating “cofactors” $C_k = \prod\limits_{j\neq k}(c_k - c_j)$? yeah, vectorization is another option. (I'm using numpy in my case.) But the polynomial coefficients are huge and are ill-conditioned; I have to work with the roots directly in order to keep numerical errors low. Jan 1 revised Is there a faster algorithm than $O(n^2)$ for calculating “cofactors” $C_k = \prod\limits_{j\neq k}(c_k - c_j)$? added 289 characters in body Jan 1 asked Is there a faster algorithm than $O(n^2)$ for calculating “cofactors” $C_k = \prod\limits_{j\neq k}(c_k - c_j)$? Dec 23 accepted residue equation for the denominator in a Padé approximant for $e^{-x}$ Dec 23 accepted solving a series of nonlinear equations for the zeros of Bessel polynomials Dec 20 revised residue equation for the denominator in a Padé approximant for $e^{-x}$ added 22 characters in body Dec 20 revised residue equation for the denominator in a Padé approximant for $e^{-x}$ added 889 characters in body Dec 20 answered residue equation for the denominator in a Padé approximant for $e^{-x}$ Dec 20 revised residue equation for the denominator in a Padé approximant for $e^{-x}$ added 69 characters in body Dec 20 asked residue equation for the denominator in a Padé approximant for $e^{-x}$ Dec 20 answered solving a series of nonlinear equations for the zeros of Bessel polynomials Dec 19 comment solving a series of nonlinear equations for the zeros of Bessel polynomials more info on Bessel polynomials at dlmf.nist.gov/18.34 Dec 19 asked solving a series of nonlinear equations for the zeros of Bessel polynomials Dec 18 comment roots of Padé approximating polynomials to the exponential function and Gonnet/Guettel/Trefethen's paper which also seems very relevant but I can't figure out how to apply it: guettel.com/download/gonnet_guettel_trefethen.pdf which I Dec 18 comment roots of Padé approximating polynomials to the exponential function Then we have Saff and Varga's paper On the Zeros and Poles of Padé Approximants to $e^z$ which looks tantalizingly relevant, but they don't compute the roots numerically, they just have proofs of general behavioral of where they are and aren't. Dec 18 revised roots of Padé approximating polynomials to the exponential function added 668 characters in body; edited tags Dec 17 asked roots of Padé approximating polynomials to the exponential function