Re: [NTG-context] to pass an argument in a macro

25 Dec 2012

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Am 23.12.2012 um 02:58 schrieb Roland Thiers  
:
...
Bonjour,
I am new in ConTeXt. I love its features. I need some (or a lot of)  
help.
I tried to get a macro which compute some values for a math function.
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Le 23 déc. 12 à 18:43, Wolfgang Schuster a écrit :
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\startluacode
userdata         = userdata       or {}
userdata.roland = userdata.roland or {}
local roland = userdata.roland
function roland.f(x)
  context(x*x*x)
end
function roland.table(min,max,step)
  local min  = tonumber(min)
  local max  = tonumber(max)
  local step = tonumber(step)
  context.starttable({string.format("|*{%d}{l|}",max-min+2)})
  context.HL()
  context.VL()
  context("x")
  for i=min,max do
      context.NC()
      context(min+(i-1)*step)
  end
  context.VL()
  context.FR()
  context.HL()
  context.VL()
  context("f(x)")
  for i=min,max do
      context.NC()
      roland.f(min+(i-1)*step)
  end
  context.VL()
  context.AR()
  context.HL()
  context.stoptable()
end
\stopluacode
\define[3]\TableFuntion
 {\ctxlua{userdata.roland.table("#1","#2","#3")}}
\starttext
\TableFuntion{1}{6}{1}
\TableFuntion{2}{7}{1}
\stoptext
Wolfgang
I read with care (maybe) your code above, Wolfgang (thanks again !) et  
had a look in "programming in lua" to get a better idea of the object  
table, new in lua too :-)
I have some more questions :
- when one create a table doing this : userdata=userdata or {}, is it  
only to be sure that "userdata" is not actually a variable which  
exists (with
a non nil value) ? Less safely we could write : userdata={} ?
-  arguments for the user.data.table function are given as strings : "  
#1" and changed in numbers in the body of the function. I noticed that  
it was possible to
give numbers directly. is there always better to do like this ? (enter  
strings et use tonumber)
- I found the command \define in context garden and saw it's the same  
than \unexpanded\def , there is a link to the définitions of the TeX  
primitives but
I could'nt find \unexpanded\def  (\def was very instructive however).
- I changed slightly the code to obtain a range (x between min and max  
with a step) and to choose a round-way.
I failed to find a context way to get rounded numbers, so I did a  
workaround (a another function) with help from "programming in lua". I  
would like a more straight (context) way.

Here is the code :

\startluacode
-- userdata         = userdata       or {} 
-- userdata["roland"] = userdata["roland"] or {} 
userdata=userdata or {}
userdata["roland"]=userdata["roland"] or {}
local roland = userdata["roland"]

function roland.f(x)
return math.log(x)
end

function roland.round (number, approx)
   local power = 10^(approx or 0)
context(math.floor(number * power + 0.5) / power)
end

function roland.table(min,max,step,approx)
         local min  = tonumber(min)
         local max  = tonumber(max)
         local step = tonumber(step)
         local nbrcol = tonumber((max-min)*(1/step)+2)
         local approx = tonumber(approx)
         context.starttable({string.format("|*{%d}{l|}",nbrcol)})
         context.HL()
         context.VL()
         context("x")
         for i=1,(nbrcol-1) do
                 context.NC()
                 context(min+(i-1)*step)
         end
         context.VL()
         context.FR()
         context.HL()
         context.VL()
         context("f(x)")
         for i=1,(nbrcol-1) do
                 context.NC()

local result=roland.f(min+(i-1)*step)
roland.round(result,approx)
         end
         context.VL()
         context.AR()
         context.HL()
         context.stoptable()
end

\stopluacode
\define[4]\TableFuntion
  {\ctxlua{userdata.roland.table("#1","#2","#3","#4")}}

\starttext
\TableFuntion{2}{6}{0.5}{2}
\blank[2*big]
\TableFuntion{1}{16}{1}{}
\blank[2*big]
\TableFuntion{2}{4}{2}{5}
\blank[2*big]
\TableFuntion{0.2}{2}{0.2}{3}
\stoptext

  Best regards, Roland
Happy Christmas to all Context users !
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