5

I'm trying to get a list of unique random integers within an interval with the luarandom package.

Here is a MWE, adapted from the package documentation:

\documentclass{article}
\usepackage{luarandom}
\usepackage{multido}
\begin{document}

\makeRandomNumberList{1}{30}{5}% works
% \makeRandomNumberList{2}{30}{5}% hangs
\multido{\iA=1+1}{5}{\getNumberFromList{\iA}, }


\end{document}

This gives five unique integers between 1 and 30. But I don't want 1 to be in my list. If I change the {1} to a {2}, as in the commented-out line, LaTeX seems to get into an infinite loop.

The lua code inside the luarandom package (copied below) isn't documented, so I can't trace what's going on easily. But it seems like the allFound(R) may not ever be returning true?

RandomNumbers = {}

function allFound(R)
  local r1 = R[1]
  local i
  for i=2,#R do 
    r1 = r1 and R[i]
    if not r1 then return false end 
  end
  return true
end


function makeRandomNumberList(l,r,n)
  RandomNumbers = {}
  math.randomseed(os.time())
  local R = {}
  local i,j
  for i=1,n do R[i] = false end
  repeat
    local rand = math.random(l,r)
    if not R[rand] then
      R[rand] = true
      RandomNumbers[#RandomNumbers+1] = rand
    end
  until allFound(R)
end


function makeSimpleRandomNumberList(l,r,n)
  RandomNumbers = {}
  math.randomseed(os.time()/3)
  local i
  for i=1,n do RandomNumbers[#RandomNumbers+1] = math.random(l,r) end
end


function getRand(i)
 tex.print(RandomNumbers[i])
end
Matthew Leingang
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1 Answers1

6

The package documentation is very sparse but it looks like a Lua programming error, I think the intended definition is

\documentclass{article}
\usepackage{luarandom}
\directlua{
function makeRandomNumberList(l,r,n)
  RandomNumbers = {}
  math.randomseed(os.time())
  local R = {}
  local i,j
  for i=1,n do R[i] = false end
  repeat
    local rand = math.random(l,r)
    if not R[rand+1-l] then
      R[rand+1-l] = true
      RandomNumbers[\string#RandomNumbers+1] = rand
    end
  until allFound(R)
end
}
\usepackage{multido}
\begin{document}

%\makeRandomNumberList{1}{30}{5}% works
\makeRandomNumberList{2}{30}{5}% hangs
\multido{\iA=1+1}{5}{show\iA\getNumberFromList{\iA}, }


\end{document}
David Carlisle
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