mirror of https://github.com/CGAL/cgal
143 lines
3.6 KiB
C++
143 lines
3.6 KiB
C++
// Copyright (c) 2003 INRIA Sophia-Antipolis (France).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you may redistribute it under
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// the terms of the Q Public License version 1.0.
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// See the file LICENSE.QPL distributed with CGAL.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$ $Date$
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//
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//
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// Author(s) : Menelaos Karavelas <mkaravel@cse.nd.edu>
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#ifndef CGAL_FUNCTIONS_ON_SIGNS_H
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#define CGAL_FUNCTIONS_ON_SIGNS_H
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#include <CGAL/enum.h>
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CGAL_BEGIN_NAMESPACE
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#if 0
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inline
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Sign
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operator*(const Sign &s1, const Sign &s2)
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{
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if ( s1 == ZERO || s2 == ZERO ) return ZERO;
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if ( s1 == s2 ) return POSITIVE;
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return NEGATIVE;
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}
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#endif
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template < class RT >
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Sign
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sign_a_plus_b_x_sqrt_c(const RT &a, const RT &b, const RT &c)
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{
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// computes the sign of quantity: a + b * sqrt(c)
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CGAL_assertion( !(CGAL::is_negative(c)) );
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Sign sa = CGAL::sign(a);
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if ( CGAL::sign(c) == ZERO ) return sa;
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Sign sb = CGAL::sign(b);
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if ( sa == sb ) return sa;
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if ( sa == ZERO ) return sb;
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return Sign( sa * CGAL::compare( CGAL::square(a),
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c * CGAL::square(b) )
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);
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}
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template < class RT >
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Sign
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sign_a_x_sqrt_c_plus_b_x_sqrt_d(const RT &a, const RT &b,
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const RT &c, const RT &d)
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{
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// computes the sign of quantity: a * sqrt(c) + b * sqrt(d)
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CGAL_assertion( !(CGAL::is_negative(c)) );
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CGAL_assertion( !(CGAL::is_negative(d)) );
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Sign sb = CGAL::sign(b);
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if ( CGAL::sign(d) == ZERO ) return CGAL::sign(a * c);
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if ( CGAL::sign(c) == ZERO ) return sb;
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Sign sa = CGAL::sign(a);
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if ( sa == sb ) return sa;
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if ( sa == ZERO ) return sb;
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return Sign( sa * CGAL::compare( CGAL::square(a) * c,
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CGAL::square(b) * d )
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);
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}
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template < class RT >
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Sign
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sign_a_plus_b_x_sqrt_e_plus_c_x_sqrt_f(const RT &a, const RT &b,
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const RT &c, const RT &e,
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const RT &f)
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{
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// computes the sign of quantity: a + b * sqrt(e) + c * sqrt(f)
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CGAL_assertion( !(CGAL::is_negative(e)) );
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CGAL_assertion( !(CGAL::is_negative(f)) );
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Sign s_a_plus_b_x_sqrt_e = sign_a_plus_b_x_sqrt_c(a, b, e);
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if ( CGAL::sign(f) == ZERO ) return s_a_plus_b_x_sqrt_e;
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Sign sc = CGAL::sign(c);
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if ( s_a_plus_b_x_sqrt_e == sc ) return sc;
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if ( s_a_plus_b_x_sqrt_e == ZERO ) return sc;
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return s_a_plus_b_x_sqrt_e *
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sign_a_plus_b_x_sqrt_c(CGAL::square(a) + CGAL::square(b) * e
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- CGAL::square(c) * f,
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RT(2) * a * b, e);
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}
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template < class RT >
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Sign
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sign_a_plus_b_x_sqrt_e_plus_c_x_sqrt_f_plus_d_sqrt_e_x_f(const RT &a,
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const RT &b,
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const RT &c,
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const RT &d,
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const RT &e,
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const RT &f)
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{
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// computes the sign of quantity:
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// a + b * sqrt(e) + c * sqrt(f) + d * sqrt(e * f)
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CGAL_assertion( !(CGAL::is_negative(e)) );
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CGAL_assertion( !(CGAL::is_negative(f)) );
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Sign s_a_plus_b_sqrt_e = sign_a_plus_b_x_sqrt_c(a, b, e);
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Sign s_c_plus_d_sqrt_e = sign_a_plus_b_x_sqrt_c(c, d, e);
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if ( s_a_plus_b_sqrt_e == s_c_plus_d_sqrt_e )
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return s_a_plus_b_sqrt_e;
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if ( s_a_plus_b_sqrt_e == ZERO )
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return s_a_plus_b_sqrt_e;
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return s_a_plus_b_sqrt_e *
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sign_a_plus_b_x_sqrt_c(CGAL::square(a) + CGAL::square(b) * e
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- CGAL::square(c) * f
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- CGAL::square(d) * e * f,
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RT(2) * (a * b - c * d * f),
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e);
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}
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CGAL_END_NAMESPACE
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#include <CGAL/more_functions_on_signs.h>
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#endif // CGAL_FUNCTIONS_ON_SIGNS_H
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