Fichier fig002.mp (figure 2) — Modifié le 28 Mars 2008 à 22 h 14
prologues:=2;
vardef pgcd(expr A,B) =
save a,b,r;
numeric a,b,r;
a := A; b := B;
forever:
r := a mod b;
a := b; b := r;
exitunless r > 0;
endfor;
a
enddef;
vardef prem(expr P)=
boolean reponse;
reponse=false;
numeric div;
div=0;
if P=1:
div:=1;
else:
for g=2 upto P-1:
if (pgcd(P,g)<>1):
div:=div+1;
fi;
endfor;
fi;
if div=0:
reponse:=true;
fi;
reponse
enddef;
vardef ulam(expr nb,pas)=
save $;
picture $;
$=image(
if prem(nb)=true:
fill fullcircle scaled 8mm withcolor 0.9white;
label(TEX(""&decimal(nb)&""),(0,0));
else:
label(btex $\star$ etex,(0,0));
fi;
pair ptd;
ptd=(0,0);
u:=8mm;
k:=nb;
for l=1 upto pas:
if (l mod 2)=1:
for j=1 upto l:
k:=k+1;
if prem(k)=true:
fill fullcircle scaled 8mm shifted (ptd+u*(0,j)) withcolor 0.9white;
label(TEX(""&decimal(k)&""),ptd+u*(0,j));
else:
label(btex $\star$ etex,ptd+u*(0,j));
fi;
endfor;
ptd:=ptd+u*(0,l);
for j=1 upto l:
k:=k+1;
if prem(k)=true:
label(TEX(""&decimal(k)&""),ptd+u*(j,0));
else:
label(btex $\star$ etex,ptd+u*(j,0));
fi;
endfor;
ptd:=ptd+u*(l,0);
fi;
if (l mod 2)=0:
for j=1 upto l:
k:=k+1;
if prem(k)=true:
label(TEX(""&decimal(k)&""),ptd+u*(0,-j));
else:
label(btex $\star$ etex,ptd+u*(0,-j));
fi;
endfor;
ptd:=ptd+u*(0,-l);
for j=1 upto l:
k:=k+1;
if prem(k)=true:
label(TEX(""&decimal(k)&""),ptd+u*(-j,0));
else:
label(btex $\star$ etex,ptd+u*(-j,0));
fi;
endfor;
ptd:=ptd+u*(-l,0);
fi;
endfor;
);
$
enddef;
input TEX;
beginfig(1);
draw ulam(1,10);
endfig;
beginfig(2);
draw ulam(41,15);
endfig;
end