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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:flutter/foundation.dart';
import 'tolerance.dart';
export 'tolerance.dart' show Tolerance;
/// The base class for all simulations.
/// A simulation models an object, in a one-dimensional space, on which particular
/// forces are being applied, and exposes:
/// * The object's position, [x]
/// * The object's velocity, [dx]
/// * Whether the simulation is "done", [isDone]
/// A simulation is generally "done" if the object has, to a given [tolerance],
/// come to a complete rest.
/// The [x], [dx], and [isDone] functions take a time argument which specifies
/// the time for which they are to be evaluated. In principle, simulations can
/// be stateless, and thus can be queried with arbitrary times. In practice,
/// however, some simulations are not, and calling any of these functions will
/// advance the simulation to the given time.
/// As a general rule, therefore, a simulation should only be queried using
/// times that are equal to or greater than all times previously used for that
/// simulation.
/// Simulations do not specify units for distance, velocity, and time. Client
/// should establish a convention and use that convention consistently with all
/// related objects.
abstract class Simulation {
/// Initializes the [tolerance] field for subclasses.
Simulation({ this.tolerance = Tolerance.defaultTolerance });
/// The position of the object in the simulation at the given time.
double x(double time);
/// The velocity of the object in the simulation at the given time.
double dx(double time);
/// Whether the simulation is "done" at the given time.
bool isDone(double time);
/// How close to the actual end of the simulation a value at a particular time
/// must be before [isDone] considers the simulation to be "done".
/// A simulation with an asymptotic curve would never technically be "done",
/// but once the difference from the value at a particular time and the
/// asymptote itself could not be seen, it would be pointless to continue. The
/// tolerance defines how to determine if the difference could not be seen.
Tolerance tolerance;
String toString() => objectRuntimeType(this, 'Simulation');