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// FILE MODDATA.CC: Implementation of member functions for class moddata
//////////////////////////////////////////////////////////////////////////
//
// Copyright 1990-2012 John Cremona
//
// This file is part of the eclib package.
//
// eclib is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// eclib is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License
// along with eclib; if not, write to the Free Software Foundation,
// Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
//
//////////////////////////////////////////////////////////////////////////
#include <eclib/moddata.h>
#include <eclib/arith.h>
level::level(long n, long neigs)
{
//cout<<"Creating a class level with n = " << n << endl;
modulus=n;
plist=pdivs(n); npdivs=plist.size();
dlist=posdivs(n); ndivs=dlist.size();
nap=neigs;
primelist=plist;
primevar pr; long p; p0=0;
while(primelist.size()<(unsigned)nap)
{
p=pr;
if (ndivides(p,modulus))
{
if(p0==0) p0=p;
primelist.push_back(p);
}
pr++;
}
sqfac=1;
for(long ip=0; ip<npdivs; ip++)
{
p = plist[ip];
if(::divides(p*p,n)) sqfac*=p;
}
long rootn=(long)(sqrt((double)n)+0.1); // rounded down
squarelevel=(n==rootn*rootn);
}
long bezout_x(long aa, long bb, long& xx)
{long a,b,c,x,oldx,newx,q;
oldx = 1; x = 0; a = aa; b = bb;
while (b!=0)
{ q = a/b;
c = a - q*b; a = b; b = c;
newx = oldx - q*x; oldx = x; x = newx;
}
if (a<0) {xx=-oldx; return(-a);}
else {xx= oldx; return( a);}
}
moddata::moddata(long n) :level(n)
{
// cout << "In constructor moddata::moddata.\n";
long i,p,x,d,nd,nnoninv;
phi=psi=modulus;
for(i=0; i<npdivs; i++)
{ p = plist[i];
phi -= phi/p;
psi += psi/p;
}
nsymb = psi;
nsymb1 = 2*modulus-phi;
nsymb2 = nsymb-nsymb1;
invlist.resize(modulus); //codes
noninvlist.resize(modulus-phi); //list of non-units
noninvdlist.resize(modulus-phi); //list of divisors for each nonunit
gcdtable.resize(modulus); //list of gcds mod N
unitdivlist.resize(modulus); //list of units s.t. u*res | N
nnoninv=0;
for (i=0; i<modulus; i++) //set up codes
{ d = bezout_x(i,modulus,x);
gcdtable[i]=d;
if (d==1) {unitdivlist[i] = invlist[i] = reduce(x); }
else
{invlist[i]=-nnoninv;
noninvlist[nnoninv]=i;
noninvdlist[nnoninv]=-1;
if (d<modulus)
{
for (nd=0; (nd<ndivs)&&(dlist[nd]!=d); nd++) ;
noninvdlist[nnoninv]=nd;
}
nnoninv++;
if(::gcd(x,modulus)!=1) // adjust x so coprime to N
{
long m=modulus/d, mm, mpower, mmold,u,v;
mpower=mm=m; mmold=1;
while(mm!=mmold)
{
mpower=xmodmul(m,mpower,modulus);
mmold=mm;
mm=::gcd(mpower,modulus);
}
bezout(mm,modulus/mm,u,v);
// Must be careful of overflow!
x = (x*v)%mm;
x = (x*(modulus/mm))%modulus;
x = (x+(u*mm))%modulus;
}
unitdivlist[i]=x;
}
}
if (ndivs>0) {dstarts.resize(ndivs);}
}
void moddata::display() const
{
cout << "Level = " << modulus << "\n";
cout << "Number of symbols = " << nsymb << "\n";
cout << ndivs << " non-trivial divisors: " << dlist << endl;
cout << npdivs << " prime divisors: " << plist << endl;
cout << "invlist: " << invlist << endl;
cout << "noninvlist: " << noninvlist << endl;
cout << "noninvdlist: " << noninvdlist << endl;
cout << "gcdtable: " << gcdtable << endl;
cout << "unitdivlist: " << unitdivlist << endl;
}
string of_filename(long n, char c)
{
stringstream s;
s << getenv_with_default("OF_DIR","./newforms");
s << "/" << c << n;
return s.str();
}
string nf_filename(long n, char c)
{
stringstream s;
s << getenv_with_default("NF_DIR","./newforms");
s << "/" << c << n;
return s.str();
}
string small_nf_filename(long n, char c)
{
stringstream s;
s << getenv_with_default("SNF_DIR","./smallnf");
s << "/" << c << n;
return s.str();
}
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