```rgcd(a,b)=
{
[a,b] = [abs(a), abs(b)];
while (b > 0.01, [a,b] = [b,a%b]);
a;
}

global(nf, km, m, clh, R, areg, re, res, mreg);

f(a,b, nf,v,ind)=
{ my(u, vreg);
my(n = idealnorm(nf, a + b*variable(nf.pol)));
my(mv = vectorv(#v));
forprime (p=2, #ind,
my (l = valuation(n,p));
if (l,
my(cp, j = ind[p]);
n /= p^l; cp = v[j][2];
while((a+b*cp)%p,
j++; cp = v[j][2]
);
mv[j] = l
)
);
if (n!=1, return);
my (r1 = nf.sign[1]);

/* found a relation */
vreg = vectorv(#re,j,
u = a+b*re[j];
if (j<=r1, abs(u), norm(u))
);
mreg = concat(mreg, log(vreg));
m = concat(m, mv);
areg = concat(areg, a+b*t);
print1("(" res++ ": " a "," b ")");
}

clareg(pol, plim=19, lima=50, extra=5)=
{ my(coreg,lireg,r1,ind,fa,co,a,b,mh,ms,mhs,mregh);

nf=nfinit(pol); pol=nf.pol;
re = nf.roots; r1=nf.sign[1];
if (nf.index > 1, /* power basis <==> index = 1 */
error("sorry, the case 'index>1' is not implemented")
);
printf("discriminant = %s, signature = %s\n", nf.disc, nf.sign);

lireg = sum(i=1,2, nf.sign[i]); /* r1 + r2 */
ind=vector(plim); v=[];
forprime(p=2,plim,
my (w = factormod(pol,p));
my (e = w[,2]);
my (find = 0);
for(l=1,#e,
fa = lift(w[l,1]);
if (poldegree(fa) == 1,
if (!find, find=1; ind[p]=#v+1);
v = concat(v, [[p,-polcoeff(fa,0),e[l]]])
)
)
);
co = #v+extra;
res=0; print("need ", co, " relations");
areg=[]~; mreg = m = [;];
a=1; b=1; f(0,1, nf,v,ind);
while (res<co,
if (gcd(a,b)==1,
f(a,b, nf,v,ind); f(-a,b, nf,v,ind)
);
a++;
if (a*b>lima, b++; a=1)
);
print(" ");
mh=mathnf(m); ms=matsize(mh);
if (ms[1]!=ms[2],
print("not enough relations for class group: matrix size = ",ms);
return
);

mhs = matsnf(mh,4);
clh = prod(i=1,#mhs, mhs[i]);
printf("class number = %s, class group = %s\n", clh, mhs);
areg=Mat(areg); km=matkerint(m); mregh=mreg*km;
if (lireg==1,
R = 1
,
coreg = #mregh;
if (coreg < lireg-1,
print("not enough relations for regulator: matsize = ", matsize(mregh));
R = "(not given)";
,
mreg1 = mregh[1 .. lireg-1, ];
R = 0;
for(j=lireg-1,coreg,
a = matdet(mreg1[, j-lireg+2 .. j]);
R = rgcd(a,R)
)
)
);
print("regulator = " R);
}

check(lim=200) =
{ my(r1,r2,pol,z,Res,fa);

[r1,r2] = nf.sign;
pol = nf.pol;
z = 2^r1 * (2*Pi)^r2 / sqrt(abs(nf.disc)) / nfrootsof1(nf)[1];
Res = 1.; \\ Res (Zeta_K,s=1) ~ z * h * R
forprime (q=2,lim,
fa = factormod(pol,q,1)[,1];
Res *= (q-1)/q / prod(i=1, #fa, 1 - q^(-fa[i]))
);
z * clh * R / Res;
}

fu() = vector(#km, k, factorback(concat(areg, km[,k])));
```