# Fredrik Johansson

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 Name Fredrik Johansson Member for 3 years Seen 11 hours ago Website Location Age
 Apr19 comment Efficient (divergent) summation for sum of zetas at negative arguments?joro: mpmath.nsum does not work well if some terms are zero. Excluding those gives 0.081061466795328 (it does not appear possible to get much more accuracy). Apr3 comment Good Computer Package for Calculating Inverse of a Formal Power Series?Assuming you mean the compositional inverse, fmpz_poly_revert_series. flint is a good choice if you want say 10000 terms. Mar28 comment Machin-like formulas for logarithmsThese findings are very interesting (author of the blog here). The 4-term formula is some 10% faster than the 3-term formula in practice, which is not really that much but still quite nice. Getting a longer list of primes is very useful though. I can't believe I missed the section in Joerg's (great) book! Mar8 comment Efficient way for computation of derivatives of $f(x) = \zeta(1-x) + 1/x$ at integer x?Yes (if I understand your question directly), the Euler-Maclaurin formula works directly for zeta at any integer, and gives you the Stieltjes constants at $s = 1$ after just removing the singular $1/(s-1)$ term. Mar8 answered Efficient way for computation of derivatives of $f(x) = \zeta(1-x) + 1/x$ at integer x? Dec14 comment Simple lower bounds for Bell numbers (number of set partitions)?B_n >= (n/log_2(n))^n is false already for n = 47... Dec6 comment When we use Bernstein polynomials in applicationI see. Still, any polynomial can be written in the Bernstein basis, so if you are working with the Bernstein basis for computational purposes, you always have the option to choose an exact interpolant instead of "the" Bernstein polynomial $B_n(f)$. Dec5 comment When we use Bernstein polynomials in applicationI must be missing something. Surely the approximation error is $o(1/n)$ (in particular, identically zero for all but a finite number of $n$) if $f$ is any polynomial? Dec5 awarded ● Critic