Re: running lua in metafun and in ConTeXt

[Otared Kavian <otared@gmail.com>]

Hi Dalyoung,

I tested your code: it works fine with both definitions of the variable tt in your code. I am using the current LMTX version 2020.04.08 14:38.

Best regards: Otared

> On 11 Apr 2020, at 14:32, Jeong Dal <haksan@me.com> wrote:
> 
> Dear all,
> 
> I draw Pascal’s triangle with the label of each point created by using lua functions.
> As you see in the code below, I defined fact(n) and combi(n,r) using lua.
> For the calculation tt, I used two different methods.
> Both are working well when I run the given code.
> 
> But I got an error, when I added this code to a ConTeXt file composed product and components,
> and using the second method, i.e. combi(n,r). The first method is still working well.
> The error message is as following:
> 
> metapost log    > loading metafun, including plain.mp version 1.004 for metafun iv and xl
> metapost log    > 
> luatex warning  > mplib: run script: [string "return mp.print(combi(0,0 ))"]:1: attempt to call a nil value (global 'combi')
> 
> metapost log    > >> tt
> metapost log    > >> vacuous
> metapost log    > ! Equation cannot be performed (numeric=vacuous).
> metapost log    > <to be read again> 
> metapost log    >                    ;
> metapost log    > <for(0)> ...&decimal(0)&","&decimal(EXPR0)&" ))");
> metapost log    >                                                   now:=start+(EXPR0)*right*d...
> metapost log    > <for(0)> ....now--(now+A);draw.now--(now+B);endfor
> metapost log    >                                                   ; ENDFOR
> metapost log    > <*> ...now+A); draw now -- (now+B); endfor; endfor
> metapost log    >                                                   ;;
> 
> I don’t know why the same code treated differently.
> I think that I have to do something more in luacode which I don’t know.
> Comments are wellcome!
> 
> Best regards,
> 
> Dalyoung
> 
> %%%%%%%
> 
> \startluacode
> function fact (n)
>   if n <= 0 then
>     return 1
>   else
>     return n * fact(n-1)
>   end
> end
> function combi(n,r)
>    return fact(n)/(fact(r)*fact(n-r))
> end
> \stopluacode
> \startbuffer[fig121]
> numeric n,r,s,u,dx,dy,tt; u := 1.8cm;
> path p, q;
> pair A,B,start,now;
> A := dir(210)*u;
> B := dir(-30)*u;
> dy := sind(30)*u;
> dx := 2*cosd(30)*u;
> for n=0 upto 4:
>    start := n*dir(210)*u;
>    for r=0 upto n:
>       s := n-r;
> %     tt := lua("mp.print(fact(" & decimal n & ")/(fact(" & decimal r & ")*fact(" & decimal s &" )))");
>       tt := lua("mp.print(combi(" & decimal n & "," &  decimal r & " ))");
>       
>       now := start+r*right*dx;
>       dotlabel.top(textext("$\displaystyle {" & decimal n & "\choose" & decimal r & "} = "& decimal tt & "$"),now);
>       draw now -- (now+A);
>       draw now -- (now+B);
>    endfor;
> endfor;
> \stopbuffer
> \starttext
> \switchtobodyfont[11pt]
> \processMPbuffer[fig121]
> \switchtobodyfont[12pt]
> \stoptext
> 
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