#  Copyright (c) 1997-2018
#  Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Berlin, Germany)
#  http://www.polymake.org
#
#  This program 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, or (at your option) any
#  later version: http://www.gnu.org/licenses/gpl.txt.
#
#  This program 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.
#-------------------------------------------------------------------------------

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###
###  CyclicQuotient rules
###
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object CyclicQuotient {

   rule N, Q : DUAL_CONTINUED_FRACTION {
      my $check = cf2rational($this->DUAL_CONTINUED_FRACTION);
      $this->N = new Integer(numerator($check));
      $this->Q = new Integer(numerator($check) - denominator($check));
   }

   rule DUAL_CONTINUED_FRACTION : N, Q {
      my $check = new Rational($this->N, ($this->N)-($this->Q));
      $this->DUAL_CONTINUED_FRACTION = rational2cf($check);
   }

   rule RAYS : N, Q {
      $this->RAYS = new Matrix([1,0],[-$this->Q, $this->N]);
   }

   rule MAXIMAL_CONES : {
      $this->MAXIMAL_CONES = [[0, 1]];
   }

   rule CONTINUED_FRACTION : N, Q {
      my $check = new Rational($this->N, $this->Q);
      # print $check."\n";
      $this->CONTINUED_FRACTION = rational2cf($check);
   }

   rule N, Q : CONTINUED_FRACTION {
      my $check = cf2rational($this->CONTINUED_FRACTION);
      $this->N = new Integer(numerator($check));
      $this->Q = new Integer(denominator($check));
   }
}


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###
###  User functions
###
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# @category Continued fractions
# Compute the continued fraction corresponding to a rational number //r//.
# @param Rational r
# @return Vector<Integer>
user_function rational2cf(Rational) {
   my ($check) = @_;
   my @result = ();
   while ($check != 0) {
      push @result, new Integer(ceil($check));
      $check = ceil($check)- $check;
      $check = $check !=0 ? 1/$check : 0;
      # print $check."\n";
   }
   return new Vector<Integer>(\@result);
}

# @category Continued fractions
# Compute the rational number corresponding to a continued fraction.
# @param Vector<Integer> v
# @return Rational
user_function cf2rational(Vector<Integer>) {
   my($v) = @_;
   my @chain = @$v;
   my $check = new Rational(pop @chain);
   my $s = @chain;
   while($s > 0){
      $check = (new Rational(pop @chain)) - 1/$check;
      $s = @chain;
   }
   return $check;
}

