/usr/include/eclib/desc2.h is in libec-dev 20160720-2.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | // desc2.h: declaration of second descent (via 2-isogeny) procedure
//////////////////////////////////////////////////////////////////////////
//
// 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
//
//////////////////////////////////////////////////////////////////////////
int desc2(const bigint& c, const bigint& d1, const bigint& d2,
const vector<bigint>& plist, const vector<bigint>& supp, const vector<bigint>& bgens,
long mask, double hlim,
bigint& x, bigint& y, bigint& z, int verb, int selmer_only=0, int alldesc=0);
// Works on homogeneous space (d1,0,c,0,d2)
// Returns
// -1 if it certainly has no points (if no ELS descendents)
// +1 if it has a point (coordinates returned in x, y, z)
// 0 if undecided (ELS descendents exist but no rational points were found)
// if alldesc==1 it does not stop when it finds one descendent with a point on it,
// but goes on to look at all the others.
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