CGAL 4.7 - Algebraic Kernel
AlgebraicKernel_d_2::ApproximateRelativeX_2 Concept Reference

## Definition

A model of AlgebraicKernel_d_2::ApproximateRelativeX_2 is an AdaptableBinaryFunction that computes an approximation of the $$x$$-coordinate of an AlgebraicKernel_d_2::Algebraic_real_2 value with respect to a given relative precision.

Refines:
AdaptableBinaryFunction
AlgebraicKernel_d_2::ApproximateAbsoluteY_2
AlgebraicKernel_d_1::ApproximateAbsolute_1
AlgebraicKernel_d_1::ApproximateRelative_1

## Types

typedef std::pair
< AlgebraicKernel_d_1::Bound,
AlgebraicKernel_d_1::Bound
result_type

typedef
AlgebraicKernel_d_2::Algebraic_real_2
first_argument_type

typedef int second_argument_type

## Operations

result_type operator() (const first_argument_type &v, const second_argument_type &a)
The function computes a pair $$p$$ of AlgebraicKernel_d_1::Bound, where $$p.first$$ represents the lower approximation and $$p.second$$ represents the upper approximation. More...

## Member Function Documentation

 result_type AlgebraicKernel_d_2::ApproximateRelativeX_2::operator() ( const first_argument_type & v, const second_argument_type & a )

The function computes a pair $$p$$ of AlgebraicKernel_d_1::Bound, where $$p.first$$ represents the lower approximation and $$p.second$$ represents the upper approximation.

The pair $$p$$ approximates the $$x$$-coordinate $$x$$ of the AlgebraicKernel_d_2::Algebraic_real_2 value $$v$$ with respect to the relative precision $$a$$.

Postcondition
$$p.first <= x$$
$$x <= p.second$$
$$(x - p.first) <= 2^{-a} |x|$$
$$(p.second - x) <= 2^{-a} |x|$$