Deterministic system

Source: Wikipedia, the free encyclopedia.

In mathematics, computer science and physics, a deterministic system is a system in which no randomness is involved in the development of future states of the system.[1] A deterministic model will thus always produce the same output from a given starting condition or initial state.[2]

In physics

parabolic projectile motion showing velocity vector
The trajectory of a projectile launched from a cannon is modeled by an ODE that is derived from Newton's second law.

Physical laws that are described by

differential equations
represent deterministic systems, even though the state of the system at a given point in time may be difficult to describe explicitly.

In quantum mechanics, the Schrödinger equation, which describes the continuous time evolution of a system's wave function, is deterministic. However, the relationship between a system's wave function and the observable properties of the system appears to be non-deterministic.

In mathematics

The systems studied in

Lyapunov exponents
.

Markov chains and other random walks are not deterministic systems, because their development depends on random choices.

In computer science

A deterministic

deterministic Turing machine
, is a model of computation such that the successive states of the machine and the operations to be performed are completely determined by the preceding state.

A deterministic algorithm is an algorithm which, given a particular input, will always produce the same output, with the underlying machine always passing through the same sequence of states. There may be non-deterministic algorithms that run on a deterministic machine, for example, an algorithm that relies on random choices. Generally, for such random choices, one uses a pseudorandom number generator, but one may also use some external physical process, such as the last digits of the time given by the computer clock.

A pseudorandom number generator is a deterministic algorithm, that is designed to produce sequences of numbers that behave as random sequences. A hardware random number generator, however, may be non-deterministic.

Others

In economics, the Ramsey–Cass–Koopmans model is deterministic. The stochastic equivalent is known as real business-cycle theory.

See also

References

  1. ^ deterministic system - definition at The Internet Encyclopedia of Science
  2. ^ Dynamical systems at Scholarpedia