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 Apr 15 awarded Revival Mar 21 comment Level of Rigor in Mathematical Physics Feb 2 reviewed Leave Closed Too old to start math Feb 2 reviewed Close What's the meaning of $C^1(R)$? Feb 2 reviewed Looks OK Show that $\hat{\theta}$ is an unbiased estimator of $\theta$ Jan 12 comment How calculators do trigonometry A brute force approach is to do the entire computation $50000-2\pi m$ in a higher precision arithmetic. Jan 12 comment How calculators do trigonometry My guess is that if $mod(50000,2\pi)$ is computed internally using something like $50000-2\pi m$, then the value of $2\pi m$ is going to have an error $2m$ times the error of $\pi$. As $2m = 10^4$ roughly, the error in $x=50000-2\pi m$ would be $10^{-12}$. Such error would produce an error in $sin(x)$ of order $10^{-12}$. This seems to agree with the experimental results. In any case, the operation $50000-A$ with $50000-A\approx1$ is bound to have an error of order $10^{-12}$ just because of the cancellation of digits. So one needs to find a way without subtraction. Jan 12 comment How does a calculator calculate the sine, cosine ,tangent using just a number? Could one start with $x_0=1$ and then normalize in the final step? Jan 12 comment How does a calculator calculate the sine, cosine ,tangent using just a number? I suspect that he is talking about Chebyshev interpolation based on a precomputed table. This might be faster if the precision is predetermined. Dec 16 comment Vanishing Gaussian curvature I don't think $K$ will vanish in general. Why do you expect $K=0$? Nov 14 awarded Enlightened Nov 14 awarded Nice Answer Oct 29 comment What is two-dimensional curl in terms of Stokes' theorem? Thanks for the quick response. Oct 29 comment What is two-dimensional curl in terms of Stokes' theorem? Wouldn't the adjoint of the grad be -div? Oct 13 awarded Yearling Sep 7 answered Picard theorem for ODE. Sep 2 comment Regularity for a parabolic problem with nonsmooth coefficients Do you consider accepting my answer? Sep 1 awarded Revival Jun 11 comment What special role plays the function $\pi^{\frac x\pi}$ in analysis? What is $\psi$? Jun 7 revised Inverting a complex function spelling