bernstein_univariate.hpp

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/********************************************************************
 *   This file is part of the source code of the realroot library.
 *   Author(s): Bernard Mourrain, GALAAD, INRIA
 ********************************************************************/
#ifndef realroot_bernstein_univariate_hpp
#define realroot_bernstein_univariate_hpp

namespace mmx { namespace bernstein {


    template<class VECTOR1, class VECTOR2>  
    void diff(VECTOR1& res, const VECTOR2& pol) {
        res.resize(pol.size()-1);
        for(int i=0; i< pol.size()-1;i++)
            res[i] = pol[i+1]-pol[i];
    }

    template<class VECTOR, class C>
    C eval(const VECTOR& pol, const C& U, const C& V, const C& x) {
        
        unsigned sz= pol.size();
        if(sz==0) return (C)0;

        C t = (x-U)/(V-U);
        C p[sz];
        for ( unsigned i=0; i < sz; i++ ) p[i]=pol[i];
        
        for ( unsigned r = (sz-1); r != 0; r--)
            for ( unsigned i=0; i < r; i++ )
                p[i] = (1.0-t)*p[i]+t*(p[i+1]);
        return p[0];
    }

} /* namespace mmx */ } /* namespace bernstein */ 
#endif //realroot_bernstein_univariate_hpp