#  Copyright (c) 1997-2015
#  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.
#-------------------------------------------------------------------------------


# @category Producing a polytope from other objects
# Computes the envelope for a given subdivision of points.
# @param fan::SubdivisionOfPoints sd
# @option Bool extended If True, the envelope of the extended tight span is computed.
# @return Polytope
user_function tight_span_envelope($;{extended=>0}){
   my ($sd,$options) = @_;
   if($$options{"extended"}){
      my $d = $sd->POINTS->cols()-1;
      my $vec = new Vector($sd->WEIGHTS->dim()+$d);
      $vec->slice(0,$sd->WEIGHTS->dim()) = $sd->WEIGHTS;
      my $mat = $sd->POINTS->minor(All,~[0])/unit_matrix($d);
      return new Polytope(INEQUALITIES=>$vec|$mat);
   }else{
      return new Polytope(INEQUALITIES=>$sd->WEIGHTS|$sd->POINTS->minor(All,~[0]));
   }
}



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