Dear all,
The problem is solved by using the namespace of lua as below:
I am not sure what I did is the right way.
If it is not the right way, please let me know.
Thanks for reading.
Best regards,
Dalyoung
\startluacode
P={}
combi = P
function P.fact (n)
if n <= 0 then
return 1
else
return n * P.fact(n-1)
end
end
function P.ncr(n,r)
return P.fact(n)/(P.fact(r)*P.fact(n-r))
end
combi = {
fact = fact,
ncr = ncr,
}
\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(P.fact(" & decimal n & ")/(P.fact(" & decimal r & ")*P.fact(" & decimal s &" )))");
tt := lua("mp.print(P.ncr(" & 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