Cfrgtkky

Adding coffee stains to your documents

If my documents don't have those stains, my boss / students think(s) I don't drink coffee. If he or they think I am not drinking coffee, they believe I am slacking. Thanks Hanno!

David Carlisle's Christmas 'card' at http://www.ctan.org/pkg/xii.
In fact, here it is: run this through plain TeX:

let~catcode~`76~`A13~`F1~`j00~`P2jdefA71F~`7113jdefPALLF

PA''FwPA;;FPAZZFLaLPA//71F71iPAHHFLPAzzFenPASSFthP;A$$FevP

A@@FfPARR717273F737271P;ADDFRgniPAWW71FPATTFvePA**FstRsamP

AGGFRruoPAqq71.72.F717271PAYY7172F727171PA??Fi*LmPA&&71jfi

Fjfi71PAVVFjbigskipRPWGAUU71727374 75,76Fjpar71727375Djifx

:76jelse&U76jfiPLAKK7172F71l7271PAXX71FVLnOSeL71SLRyadR@oL

RrhC?yLRurtKFeLPFovPgaTLtReRomL;PABB71 72,73:Fjif.73.jelse

B73:jfiXF71PU71 72,73:PWs;AMM71F71diPAJJFRdriPAQQFRsreLPAI

I71Fo71dPA!!FRgiePBt'el@ lTLqdrYmu.Q.,Ke;vz vzLqpip.Q.,tz;

;Lql.IrsZ.eap,qn.i. i.eLlMaesLdRcna,;!;h htLqm.MRasZ.ilk,%

s$;z zLqs'.ansZ.Ymi,/sx ;LYegseZRyal,@i;@ TLRlogdLrDsW,@;G

LcYlaDLbJsW,SWXJW ree @rzchLhzsW,;WERcesInW qt.'oL.Rtrul;e

doTsW,Wk;Rri@stW aHAHHFndZPpqar.tridgeLinZpe.LtYer.W,:jbye

A good collection of Enjoy TeX pearls diving! at GUST, Polish TeX Users Group

For more Pearls of TeX programming at TUGboat ,Volume 26 (2005), No. 3.

a basic interpreter written in tex.

see the tugboat article.

Our own Bruno LeFloch who wrote a Reversi game which runs in the console:

(Please don't try to reformat the code displayed below unless you really know what you are doing; if you do attempt a reformat, try to compile the resulting code before replacing the code here.)

% !TEX TS-program = tex

longdef3#1#2#3{}vsize5cmhsize4cmnewlinechar`*def~#1{catcode`#113~}

~QSU_VWJKLMNO@XY(|+Z'"z:qj^;/)!, ${*133}

def~#1#2{let#1#2~}~*cr[ifnum(ifcaseOor|else]fiNnumber@advanceX

expandafterZglobalYmessage~defj{[0<Q[9>Q[0<J[9>J^|_]|_]|_]|_]}

~+{count1}+1=9~_#1{@+1 1countdef#1+1_}_QJVSKWUL,'"$H!_-1'1"2+44'+55'+45"+54"~^{+NQNJ}

~:#1{#11#12#13#14#15#16#17#18}

~M#1{Y{#1}#1}~h#1#2{M#2:{ q#1}&M#2&M{*}}~q#1#2{&M{(+#1#2  O-O0]}}

~/{Y{Row and column? e.g. E6*}read_toMXjmeaningM  ;}

~j#1->#2#3#4;{Q`#2@Q-`@J`#3@J-`0;(VY{Invalid move.}

/]}~;{V0 (jS1z1z0z_S0z1z_S_z1z0z_]}~_{@,('O-]}

~z#1{{H0K#1!1{H1q}(!q]}}~q{@QS@JK[j="(HZ^'Z_2]&q|[j='ZVV($(H|Z!0]]]]}~,#1{Q#1:.}

~.#1{J#1;[0<V&[V>WWVUQLJ]]}~^#1{(#1O0O1O2O2O2O2O1O0]}

~&{!^Qmultiply!3@!^J@V(!9O1O6O1O1O2O6O2O4] }~Z{M :{&M}&M{*}}

~){'X"X"N'halign{&## *M{*}

Zh1Ah2Bh3Ch4Dh5Eh6Fh7Gh8HZ}

vfilbreak$1W(W_|0] :,$0 [0<W[1='QUJL|/];^'_1][_=WM

{(,Tie| Player [0>,-|0] wins by N[0>,-],].}Xend])})

I once spent hours learning enough TeX to format my ex-gf's resume for printing on the computing center laser printer (back when laser printing was magical) and used up most of my monthly laser printing quota printing copies of it -- all under the mistaken belief that she'd see that she was crazy to break up with me.

Not surprisingly, it turned out to be a useless waste of my time (and in retrospect, it was me that should have broken up with her). Worse, word got around that I was a "TeX expert" and I ended up spending the rest of my computer center operator job helping grad students format their theses

Solving a non-linear equation

Not typesetting the solution (actually, also typesetting the solution of course :)), but more bizarrely implementing the bisection and secant non-linear solvers in TeX!

This one is probably my best:

• 
  Is there a documentclass that produces 'endless' pages? (please take a look at percusse's comment - pure genius! :))

But there are a few of them scattered around on this site. Here are my picks:

• Shortest code causing "Emergency stop." error




• Stop LaTeX compile with a command?




• Selectively suppress generation of typeset output




• Typesetting the entire Song That Never Ends




• Malicious code and/or PDF generation




• Forcing LaTeX to produce a different PDF on each compile (never reaching a stable output)

... and, as a bonus:

• How should I convert my beamer slides to PowerPoint according to these odd specifications?

I really don't see why someone would go back to MS Office after using LaTeX... Now that's weird! ;)

EDIT: and i just remembered this one (Why facebook implemented it? But why recreate it in LaTeX? ;)):

• Text upside-down, characters rotated along baseline?

Calculating π with TeX

Gen­er­ates π, us­ing the for­mula

pi=16*arc­tan(1/5)-4*arc­tan(1/239)

and leaves the re­sult in an ar­ray xr, print­ing what it’s cal­cu­lated as it goes along.

Well, as made famous by a question of mine I have used LaTeX to make to make props for a Call of Cthulhu game. I also posted the finished product on my blog.

Then later on I used the same technique to make my teaching assistant's life a bit more interesting

Implementing the bisection method (and other numerical methods) in TikZ,

for exposition purposes.

EDIT: Great thanks to percusse for helping me improve my ifg command.

documentclass[dvipsnames]{beamer}



usepackage{lmodern}

usepackage{pgfplots}



usefonttheme[onlymath]{serif}

setbeamertemplate{navigation symbols}{}



% 'if #1 greater than #2 then #3 else #4' construct (compatible with pgfmath)

newcommand{ifg}[4]{

    pgfmathparse{(#1)>(#2)?int(1):int(0)}

    ifnumpgfmathresult=1relax%

        #3%

    else%

        #4%

    fi%

}



begin{document}



begin{frame}[fragile]

    begin{center}

    begin{tikzpicture}[scale=6]

    pgfmathsetmacro{extendxaxis}{.1}

    pgfmathsetmacro{extendyaxis}{.3}

    colorlet{acolor}{red}

    colorlet{bcolor}{OliveGreen}

    colorlet{ccolor}{orange}

    colorlet{fcolor}{blue}

    pgfmathdeclarefunction{f}{1}{pgfmathparse{.5*(exp(-#1)-#1)}} % continuous function

    pgfmathsetmacro{ao}{.2}   % lower-bound of initial bracket

    pgfmathsetmacro{bo}{1}    % upper-bound of initial bracket

    pgfmathsetmacro{co}{0}    % midpoint of inital bracket (initialised at 0)

    pgfmathtruncatemacro{n}{3}        % number of iterations



    ifxaobo % check that ao and bo are distinct 

        node[red] (0,0) {Bisection impossible: singleton initial bracket.};

    else%

        ifg{ao}{bo}{ % if ao > bo, swop them

            pgfmathsetmacro{temp}{bo}

            pgfmathsetmacro{bo}{ao}

            pgfmathsetmacro{ao}{temp}

        }{}

        % code in here

        ifg{{f(ao)*f(bo)}}{0}{%

            node[red] (0,0) {Bisection impossible: no root in initial bracket.};

        }{%

            onslide<1->{%

                pgfmathsetmacro{xmin}{ao-.5*extendxaxis*(bo-ao)}

                pgfmathsetmacro{xmax}{bo+.5*extendxaxis*(bo-ao)}

                draw[->] (xmin,0) node[left] {$0$} --

                    (xmax,0) node[right] {$x$};

                pgfmathsetmacro{ymin}{min(f(ao),f(bo))-.5*extendyaxis*abs(f(bo)-f(ao))}

                pgfmathsetmacro{ymax}{max(f(ao),f(bo))+.5*extendyaxis*abs(f(bo)-f(ao))}

                draw[->] (xmin,ymin) -- (xmin,ymax) node[left] {$f(x)$};

                draw[fcolor] plot[domain=xmin:xmax] (x,{f(x)});

            }

            pgfplotsforeachungrouped k in {1,2,...,n}{%

                pgfmathtruncatemacro{k}{k}

                pgfmathsetmacro{co}{0.5*(ao+bo)}

                pgfmathtruncatemacro{j}{k-1}

                pgfmathtruncatemacro{fromslide}{3*(k-1)+2}

                pgfmathtruncatemacro{toslide}{fromslide+2}

                onslide<fromslide-toslide>{

                    draw[thick,acolor] (ao,.1ex) --

                        (ao,-.1ex) node[below] {$a_{j}$}; % a0

                    draw[thick,bcolor] (bo,.1ex) --

                        (bo,-.1ex) node[below] {$b_{j}$}; % b0

                }

                pgfmathtruncatemacro{fromslide}{fromslide+1}

                onslide<fromslide-toslide>{%

                    draw[thick,ccolor] (co,.1ex) --

                        (co,-.1ex) node[below] {$c_{j}$};     

                }

                onslide<toslide>{%

                    coordinate (a0) at (ao,{f(ao)});     

                    draw[dashed,thin,red]  (a0 |- xmin,0) -- (a0)

                        -- (a0 -| xmin,0) node[left] {$f(a_{j})$};% dashed lines

                    draw[fill,red] (a0) circle (.05ex);            

                    coordinate (c0) at (co,{f(co)}); 

                    draw[dashed,thin,orange]   (c0 |- xmin,0) -- (c0)

                        -- (c0 -| xmin,0) node[left] {$f(c_{j})$};% dashed lines      

                    draw[fill,orange] (c0) circle (.05ex);                                 

                }

                ifg{f(ao)*f(co)}{0}{ % bisection iteration

                    pgfmathsetmacro{ao}{co}

                }{%

                    pgfmathsetmacro{bo}{co}

                }

                ifxnk%

                    pgfmathtruncatemacro{toslide}{toslide+1}

                    pgfmathtruncatemacro{j}{j+1}

                    onslide<toslide>{%

                        draw[thick,acolor] (ao,.1ex) --

                            (ao,-.1ex) node[below] {$a_{j}$}; % a0 

                        draw[thick,bcolor] (bo,.1ex) --

                            (bo,-.1ex) node[below] {$b_{j}$}; % b0 

                    }

                fi                     

            }

        }

    fi

    end{tikzpicture}

    end{center}

end{frame}

end{document}

Providing an excuse for slacking off

Just let (La)TeX burn some CPU cycles while you are relaxing.

Implementing a Turing machine simulator

(TeX is Turing complete)

Hail to the busy beaver!

Enrico “egreg” Gregorio posted this into our TeX.sx chat:

1. 
   

   Let me name it xcix.tex, because it’s in the manner of David Carlisle’s xii.tex, cf. Peter Flynn’s answer

   
   
   

   let~catcode~`x13~`q~`x~`z~`q~`H~`q~`B~`H~`j0~`jA009
   
   jlet~jlet~Hjpar ~Bjmscount~~jdef~x{q bottlez of beer}
   
   ~jw{x on the wall}~jt{jadvanceAB-1ATake one down Aand
   
   pass it around,H}B99~ji{jifnumB}~q{ji=0Nojelsejnumber
   
   Bjfi}~z{ji>1sjfiA }jloop jifnumB>0 jw, x,Hjtjw.jvskip
   
   8ptplus1ptjrepeat Time to buy some more beerjdotsjend
   
   

   
   
   

   (source link)

   
   


2. 
   

   The same as LaTeX3 version

   
   
   

   documentclass{article}
   
   usepackage{xparse}
   
   
   
   setlength{parindent}{0pt}
   
   setlength{parskip}{1.5ex}
   
   
   
   ExplSyntaxOn
   
   % user level command
   
   NewDocumentCommand{beers} { O{99} }
   
    {
   
     manual_beers_sing:n { #1 }
   
    }
   
   % variables
   
   int_new:N l_manual_beers_count_int
   
   % functions
   
   cs_new_protected:Npn manual_beers_sing:n #1
   
    {
   
     int_set:Nn l_manual_beers_count_int { #1 }
   
     prg_replicate:nn { l_manual_beers_count_int }
   
      {
   
       manual_beers_print:
   
       int_decr:N l_manual_beers_count_int
   
      }
   
     Time ~ to ~ buy ~ some ~ more ~ beer ~ dots
   
    }
   
   cs_new_protected:Npn manual_beers_print:
   
    {
   
     manual_beer_text:nn { ~ on ~ the ~ wall }{ 0 }, ~
   
     manual_beer_text:nn { } { 0 }, \
   
     Take ~ one ~ down ~ and ~ pass ~ it ~ around, \
   
     manual_beer_text:nn { ~ on ~ the ~ wall } { -1 }.par
   
    }
   
   cs_new:Npn manual_beer_text:nn #1 #2
   
    {
   
     int_case:nnF { l_manual_beers_count_int + #2 }
   
      {
   
       { 0 } { No ~ bottle ~ of ~ beer }
   
       { 1 } { 1 ~ bottle ~ of ~ beer }
   
      }
   
      {
   
       int_to_arabic:n { l_manual_beers_count_int + #2 } ~ bottles ~ of ~ beer
   
      }
   
     #1
   
    }
   
   ExplSyntaxOff
   
   begin{document}
   
   beers
   
   end{document}
   
   

   
   
   

   (source link, small correction; the code as seen above is, though, in this version, as it will appear in a manual by Enrico, which is in the moment, this code was posted, in process of writing)

   
   

This was influenced by me, because I had posted these two links:

• 99 Bottles of Beer | Language TeX/LaTeX (for compilation read comment of Kiyoshi Akima below that code)




• 99 Bottles of Beer | Language LaTeX2e loading fmtcount and tikz
  (which has a link to an older version 99 Bottles of Beer | Language LaTeX2e working with memoir and loading only ifthen)

The avremu package

…emulates an 8-bit CPU (ATmega8).