 CGAL 5.3 - 2D Placement of Streamlines
Integrator_2 Concept Reference

## Definition

The concept Integrator_2 describes the set of requirements for the second template parameter of the class CGAL::Stream_lines_2<VectorField_2,Integrator_2>. This concept provides the operation that integrates a new point from a given point with a predefined step, and according to a specified vector.

Has Models:

CGAL::Euler_integrator_2<VectorField_2>

CGAL::Runge_kutta_integrator_2<VectorField_2>

## Types

typedef unspecified_type FT
The scalar type.

typedef unspecified_type Point_2
The point type.

typedef unspecified_type Vector_2
The vector type.

typedef unspecified_type Vector_field_2
The vector field type.

## Creation

Integrator_2 ()
Default constructor.

## Operations

The following operations return the newly integrated point.

Point_2 operator() (Point_2 p, Vector_field_2 vector_field_2)
Returns the new position from the actual position defined by p, according to the vector given by vector_field_2 at p. More...

Point_2 operator() (Point_2 p, Vector_field_2 vector_field_2, FT integration_step)
As above. The integration step is defined by integration_step. More...

Point_2 operator() (Point_2 p, Vector_field_2 vector_field_2, FT integration_step, bool direction)
As above. In addition, this function integrates forward if direction is true, and backward if it is false. More...

## ◆ operator()() [1/3]

 Point_2 Integrator_2::operator() ( Point_2 p, Vector_field_2 vector_field_2 )

Returns the new position from the actual position defined by p, according to the vector given by vector_field_2 at p.

Precondition
vector_field_2.is_in_domain(p) must be true.

## ◆ operator()() [2/3]

 Point_2 Integrator_2::operator() ( Point_2 p, Vector_field_2 vector_field_2, FT integration_step )

As above. The integration step is defined by integration_step.

Precondition
vector_field_2.is_in_domain(p) must be true.

## ◆ operator()() [3/3]

 Point_2 Integrator_2::operator() ( Point_2 p, Vector_field_2 vector_field_2, FT integration_step, bool direction )

As above. In addition, this function integrates forward if direction is true, and backward if it is false.

Precondition
vector_field_2.is_in_domain(p) must be true.