CGAL 6.1 - Polynomial

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PolynomialTraits_d::PolynomialSubresultants Concept Reference
Reference Manual » Concepts

## Definition

Computes the polynomial subresultant of two polynomials \( p\) and \( q\) of type `PolynomialTraits_d::Polynomial_d` with respect to outermost variable. Let \( p=\ccSum{i=0,\ldots,n}{} p_i x^i\) and \( q=\ccSum{i=0,\ldots,m}{} q_i x^i\), where \( x\) is the outermost variable. The \( i\)-th subresultant (with \( i=0,\ldots,\min\{n,m\}\)) is defined by.

\[ \mathrm{Sres}_{i}(p,q) = \det \begin{pmatrix} p_{n} & \dots & & \dots & p_{2i-m+2} & x^{m-i-1}p \\ & \ddots & & & \vdots & \vdots\\ & & p_{n} & \dots & p_{i+1} & p \\ q_{m} & \dots & & \dots & q_{2i-n+2} & x^{n-i-1}q \\ & \ddots & & & \vdots & \vdots\\ & & q_{m} & \dots & q_{i+1} & q \end{pmatrix} \]

where \( p_i\) and \( q_i\) are set to zero if \( i<0\). In the case that \( n=m\), \( \mathrm{Sres_n}\) is set to \( q\).

The result is written in an output range, starting with the \( 0\)-th subresultant \( \mathrm{Sres}_0(p,q)\) (aka as the resultant of \( p\) and \( q\)).

Note
  This functor is optional.

Refines
  `AdaptableBinaryFunction`
  `CopyConstructible`
  `DefaultConstructible`

See also
  `Polynomial_d`
  `PolynomialTraits_d`
  `PolynomialTraits_d::Resultant`
  `PolynomialTraits_d::PrincipalSubresultants`
  `PolynomialTraits_d::PolynomialSubresultantsWithCofactors`
  `PolynomialTraits_d::SturmHabichtSequence`

## Operations
template<typename OutputIterator >
OutputIterator | operator() (Polynomial_d p, Polynomial_d q, OutputIterator out)
| computes the polynomial subresultants of \( p\) and \( q\), with respect to the outermost variable.
template<typename OutputIterator >
OutputIterator | operator() (Polynomial_d p, Polynomial_d q, OutputIterator out, int i)
| computes the polynomial subresultants of \( p\) and \( q\), with respect to the variable \( x_i\).

## Member Function Documentation

## ◆ operator()()

template<typename OutputIterator >

OutputIterator PolynomialTraits_d::PolynomialSubresultants::operator() | ( | Polynomial_d | p,
|  | Polynomial_d | q,
|  | OutputIterator | out
| ) |  |

computes the polynomial subresultants of \( p\) and \( q\), with respect to the outermost variable.

Each element is of type `PolynomialTraits_d::Polynomial_d`.