Re: Formatting numbers in LuaTeX

[Andreas Harder <aharder@uni-koblenz.de>]

Am 14.02.2010 um 13:11 schrieb Peter Münster:

> On Sun, Feb 14 2010, Andreas Harder wrote:
> 
>> 1) Is it possible to have a comma as decimal separator?
>> 
>> 2) If you look at the above definition, it works fine with +, –, /, but
>> not with *. Is it possible to expand my macro that it will also work with
>> a multiplication or even with the last two examples?
> 
> Hello Andreas,
> 
> Just a quick hack:
> 
> \usemodule[calcmath]
> \startluacode
> sqrt = math.sqrt
> pi = math.pi
> function my_equation(s, r)
> 	r = tostring(r)
> 	tex.print(s:gsub("*", "×") .. "=" .. r:gsub("%.", ","))
> end
> \stopluacode
> \def\calculate#1{\calcmath{\ctxlua{my_equation("#1", #1)}}}
> \starttext
> \startlines
>  \calculate{1+2}
>  \calculate{3/2-1}
>  \calculate{3*2}
>  \calculate{sqrt(2)}
>  \calculate{2*pi}
> \stoplines
> \stoptext

That’s nice! Thank you very much! 

I've found an posting on the LuaTeX-mailing-list and incorporated it, so one have rounded results (I didn't find a way to use "\%.2f"). So, if someone is interested:

\usemodule[calcmath]

\startluacode
  local floor = math.floor
  local round = function(n) return floor(1000*n+0.5)/1000 end

  sqrt = math.sqrt
  pi = math.pi
  function my_equation(s, r)
    r = round(r)
    r = tostring(r)
    tex.print(s:gsub("*", "$·$") .. "=" .. r:gsub("%.", ","))
  end
\stopluacode

\def\calculate#1{\calcmath{\ctxlua{my_equation("#1", #1)}}}

\starttext

\startlines
 \calculate{1+2}
 \calculate{3/2-1}
 \calculate{3*2}
 \calculate{sqrt(2)}
 \calculate{2*pi}
\stoplines

\stoptext


Greetings
	Andreas
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