Re: Metapost label - Truncating digits after decimal point

[Aditya Mahajan <adityam@umich.edu>]

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

Aditya
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