File:Prime number theorem ratio convergence.svg

DescriptionPrime number theorem ratio convergence.svg	English: A plot showing how two estimates described by the prime number theorem, ${\displaystyle {\frac {x}{\ln x}}}$ and ${\displaystyle \int _{2}^{x}{\frac {1}{\ln t}}\mathrm {d} t=Li(x)=li(x)-li(2)}$ converge asymptotically towards ${\displaystyle \pi (x)}$, the number of primes less than x. The x axis is ${\displaystyle x}$ and is logarithmic (labelled in evenly spaced powers of 10), going up to 1024, the largest ${\displaystyle x}$ for which ${\displaystyle \pi (x)}$ is currently known. The former estimate converges extremely slowly, while the latter has visually converged on this plot by 108. Source used to generate this chart is shown below.
Date	21 March 2013
Source	Own work
Author	Dcoetzee
SVG development InfoField	The SVG code is valid.   This chart was created with Mathematica.    This chart uses embedded text that can be easily translated using a text editor.

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Mathematica source to generate graph (which was then saved as SVG from Mathematica):

(* Sample both functions at 600 logarithmically spaced points between \
1 and 2^40 *)
base = N[E^(24 Log[10]/600)];
ratios = Table[{Round[base^x], 
    N[PrimePi[Round[base^x]]/(base^x/(x*Log[base]))]}, {x, 1, 
    Floor[40/Log[2, base]]}];
ratiosli = 
  Table[{Round[base^x], 
    N[PrimePi[
       Round[base^x]]/(LogIntegral[base^x] - LogIntegral[2])]}, {x, 
    Ceiling[Log[base, 2]], Floor[40/Log[2, base]]}];
(* Supplement with larger known PrimePi values that are too large for \
Mathematica to compute *)
LargePiPrime = {{10^13, 346065536839}, {10^14, 3204941750802}, {10^15,
     29844570422669}, {10^16, 279238341033925}, {10^17, 
    2623557157654233}, {10^18, 24739954287740860}, {10^19, 
    234057667276344607}, {10^20, 2220819602560918840}, {10^21, 
    21127269486018731928}, {10^22, 201467286689315906290}, {10^23, 
    1925320391606803968923}, {10^24, 18435599767349200867866}};
ratios2 = 
  Join[ratios, 
   Map[{#[[1]], N[#[[2]]]/(#[[1]]/(Log[#[[1]]]))} &, LargePiPrime]];
ratiosli2 = 
  Join[ratiosli, 
   Map[{#[[1]], N[#[[2]]]/(LogIntegral[#[[1]]] - LogIntegral[2])} &, 
    LargePiPrime]];
(* Plot with log x axis, together with the horizontal line y=1 *)
Show[LogLinearPlot[1, {x, 1, 10^24}, PlotRange -> {0.8, 1.25}], 
 ListLogLinearPlot[{ratios2, ratiosli2}, Joined -> True], 
 LabelStyle -> FontSize -> 14]

LaTeX source for labels:

$$ \left.{\pi(x)}\middle/{\frac{x}{\ln x}}\right. $$
$$ \left.{\pi(x)}\middle/{\int_2^x \frac{1}{\ln t} \mathrm{d}t}\right. $$

These were converted to SVG with [1] and then the graph was embedded into the resulting document in Inkscape. Axis fonts were also converted to Liberation Serif in Inkscape.