george2079
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 18h comment How to speed up NDSolve? You aren't going to beat the performance of native machine precision by working at lower precision. 1d comment How to calculate the slope in a data set plotted in ListPlot? LinearModelFit[data[i-10;;i+10,..]] is part of it. You really have rolled too many questions into one here. 1d comment Archimedes' Scheme to find $\pi$ i don't know that a numerical evaluation would be considered "proof".. Apr 29 comment Integrate fortran function into Mathematica try without the _ Apr 28 comment Change “ListPlot” to 16 bit accuracy? your syntax is wrong, # should be some symbol, eg to16bits[x_] := Floor[2^16*x]*2.^-16 I cant see what that will accomplish though, i.m sure that tiny roundoff is too small to discern on a plot. (Or do you mean to do that rounding at every iteration?) Apr 28 comment Simplify assuming $x$ is small reference.wolfram.com/language/ref/Series.html#26978 Apr 27 comment Jump boundary conditions I'm afraid you will need to work out your own finite difference scheme. Apr 27 comment Jump boundary conditions not sure why the downvote. Anyway NDSolve is not so general that it can handle any sort of bc you can dream up, even if mathematically valid. In this case the pde's look to be fully decoupled, so solve first for u, then use that solution as a bc as you solve for v and so on. Alternately formulate as a single unknown on domain x,0,4 Apr 27 comment Strange DiracDelta integration results in 10.4.1 do the assumptions matter? You should only need s!=0 Apr 26 comment Polynomial Equation/Function With Even Degree Order Apr 26 comment Free-fall air resistance problem Put your cursor on Exp and push F1 . You managed to invent two different incorrect expression syntaxes for the exponential. Apr 26 comment Inconsistent Integrate behavior? you can do this: Integrate[q0/(-1 + b q0^2), {q0, 0, A}] /. b -> 12 to get your conditional expression. I agree this is an inconsistency. You can also see the issue if you do Integrate[q0/(-1 + 12 q0^2), {q0, 0, 1}] you get a correct message that the integral does not converge while Integrate[q0/(-1 + 12 q0^2), {q0, 0, A}] /. A -> 1 gives an erroneous result. Apr 26 comment Polynomial Equation/Function With Even Degree Order "please write code for me" type questions are off topic. Show what you have tried. You should also clarify exactly what trig forms are permissible. Apr 26 comment I'm trying to solve a system of complex equations +1 note this works without converting to exact fractions, I think all that does for you is suppress a warning. ( You need parenthesis on (1735/10) btw ) Apr 25 comment NSolve won't act on very large powers Its not about the exact integer, this gives null results too: Cases[Table[{v, NSolve[1/x == v, x]}, {v, RandomReal[10, 1000] 10^13}], {x_, {}}] Apr 25 comment How to preview the notebook file in a file explorer just like the preview of pdf file at one time I had a script set up to auto create pdf versions of every notebook. The main point for me was so that windows search would work on the pdf's. The clutter of all the extra files gets cumbersome though. Apr 25 comment Use Map on a Function with two variables aside, just do function[a_, b_] := a+b. Return is needed in mathematica very rarely and often does not behave as you might expect. Apr 22 comment Exporting sharp corners in Bézier curves to pdf my thinking is the blunt end is the mathematically correct form. To achieve that corner in eps/pdf you need to render two separate curves that are joined so that the behavior is controlled by linejoin . Sorry I don't know off hand how to do that from within mathematica. Apr 22 comment How to Import This XYZ format file from the wikipedia page en.wikipedia.org/wiki/XYZ_file_format "There is no formal standard and several variations exist" Apr 22 comment How Do i Extract Only The Coordinates xyz (Number) From This Log file use Import[ filename , "Table" ]. From there it is straightforward to extract the data you need.