From: Hans Hagen <j.hagen@xs4all.nl>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>,
Jeong Dal <haksan@me.com>
Subject: Re: Code lua in a table
Date: Mon, 20 Jul 2020 10:36:33 +0200 [thread overview]
Message-ID: <31495829-66d7-c670-75e2-d1c538f38e9c@xs4all.nl> (raw)
In-Reply-To: <D512FBE4-D72C-4DE6-BE4E-19D2E8266604@me.com>
On 7/20/2020 7:56 AM, Jeong Dal wrote:
> Dear Fabrice,
>
> You may split Binom(n,k) function into two functions as following:
>
> see original mail
>
> Dalyoung
Best stay in a protected namespace ...
\startluacode
local function fact (n)
if n <= 0 then
return 1
else
return n * fact(n-1)
end
end
local function ncr(n,r)
return fact(n)/(fact(r)*fact(n-r))
end
userdata.P = {
fact = fact,
ncr = ncr,
}
function MP.pascal_ncr(n, r)
mp.print(ncr(n,r))
end
\stopluacode
Watch the last definition. This permits
% tt := lua("mp.print(userdata.P.ncr(" & decimal n & "," &
decimal r & " ))");
replaced by
tt := lua.MP.pascal_ncr(n,r);
which looks nicer.
\startbuffer[pt1]
numeric n, r, s, u, dx, dy, tt;
path p, q;
pair A, B, start, now;
u := 1.8cm;
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(userdata.P.ncr(" & decimal n & "," &
decimal r & " ))");
tt := lua.MP.pascal_ncr(n,r);
now := start+r*right*dx;
dotlabel.top(textext("$\displaystyle {" & decimal n &
"\choose" & decimal r & "} = "& decimal tt & "$"),now);
draw (now+A) -- now -- (now+B);
endfor;
endfor;
\stopbuffer
Now, in context lmtx we can have a different kind of abstraction. We can
do this:
function MP.pascal_ncr_x()
mp.print(ncr(mp.scan.pair()))
end
and then use:
tt := runscript("MP.pascal_ncr_x()") (n,r) ;
Of course one can decide to pick to two numerics instead, like
tt := runscript("MP.pascal_ncr_x()") n r ;
but i leave that as exercise.
% tt := runscript mp_pascal_ncr (n,r) ;
tt := pascal_ncr (n,r) ;
However, we still have the rather verbose runscript here, so we go
further, we register pascal as script:
\startluacode
metapost.registerscript("pascal_ncr",MP.pascal_ncr_x)
\stopluacode
And then define an alias at the metafun end:
\startMPextensions
newinternal mp_pascal_ncr ; mp_pascal_ncr := scriptindex "pascal_ncr" ;
def pascal_ncr =
runscript mp_pascal_ncr
enddef ;
\stopMPextensions
The internal permits this:
tt := runscript mp_pascal_ncr (n,r) ;
while the additional def permits
tt := pascal_ncr (n,r) ;
Now watch out, because we define pascal_ncr here, something
lua.MP.pascal_ncr(n,r) won't work because the last part gets expanded
because that is what mp does (i'll probably cook something for that some
day).
Now, to come back to
"I couldn’t wikify it at that time because I don’t know
how to. I’ll do it soon."
looks like you suddenly have an additional challenge,
Hans
-----------------------------------------------------------------
Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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next prev parent reply other threads:[~2020-07-20 8:36 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.1.1595152801.23549.ntg-context@ntg.nl>
2020-07-20 5:56 ` Jeong Dal
2020-07-20 8:36 ` Hans Hagen [this message]
2020-07-20 10:13 ` Fabrice Couvreur
2020-07-20 12:40 ` Jeong Dal
2020-07-20 12:54 ` Hans Hagen
2020-07-21 13:08 ` Fabrice Couvreur
2020-07-18 18:05 Fabrice Couvreur
2020-07-18 18:32 ` Wolfgang Schuster
2020-07-18 20:09 ` Fabrice Couvreur
2020-07-18 20:22 ` Wolfgang Schuster
2020-07-18 20:25 ` Fabrice Couvreur
2020-07-18 20:34 ` Fabrice Couvreur
2020-07-18 20:36 ` Wolfgang Schuster
2020-07-18 21:35 ` Otared Kavian
2020-07-18 22:05 ` Otared Kavian
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