# Re: [NTG-context] Metapost label - Truncating digits after decimal point

Thanks for this solution. Sounds small and clean. I need to learn Lua I guess.


On Tue, Dec 15, 2009 at 5:34 AM, Aditya Mahajan <adit...@umich.edu> wrote:
> On Sat, 28 Nov 2009, Curiouslearn wrote:
>
>> Hi,
>>
>> Is it possible to truncate the digits after decimal point in Metapost
>> when using textext()? Please see the minimal example below which
>> produces 1.84375. Can I just keep the first digit and have it produce
>> 1.8 ?
>>
>> Thanks.
>
> If you are using mkiv, you can use lua to truncate a number.
>
> \unexpanded\def\truncate#1{\ctxlua{context("\%.1f", #1)}}
>
> \startMPdefinitions
>  def truncatedtext(expr s) =
>    textext("\truncate{" & s & "}")
>  enddef ;
> \stopMPdefinitions
>
> \starttext
> \startuseMPgraphic{Figure}
>  u := 1cm;
>  pickup pencircle scaled 2pt; % default pen thickness
>  %TheFunction
>  vardef f(expr x) =
>          (10/x)-x*((0.5)**x)
>  enddef;
>  %Labels
>  %label.lft(textext("\truncate{" & decimal f(5) & "}"),(0,f(5)) scaled u);
>  label.lft(truncatedtext(decimal f(5)),(0,f(5)) scaled u);
> \stopuseMPgraphic
> \useMPgraphic{Figure}
>
>
> \stoptext
>
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