Position

Position refers to the spatial location (rather than orientation) of an entity. The term may also refer to:

Science and mathematics

Humanities, law and economics

Games and recreation

Human activity

Position operator

In quantum mechanics, the position operator is the operator that corresponds to the position observable of a particle. The eigenvalue of the operator is the position vector of the particle.

Introduction

In one dimension, the square modulus of the wave function, , represents the probability density of finding the particle at position . Hence the expected value of a measurement of the position of the particle is

Accordingly, the quantum mechanical operator corresponding to position is , where

The circumflex over the x on the left side indicates an operator, so that this equation may be read The result of the operator x acting on any function ψ(x) equals x multiplied by ψ(x). Or more simply, the operator x multiplies any function ψ(x) by x.

Eigenstates

The eigenfunctions of the position operator, represented in position space, are Dirac delta functions. To show this, suppose that is an eigenstate of the position operator with eigenvalue . We write the eigenvalue equation in position coordinates,

Position (finance)

In financial trading, a position is a binding commitment to buy or sell a given amount of financial instruments, such as securities, currencies or commodities, for a given price.

The term "position" is also used in the context of finance for the amount of securities or commodities held by a person, firm, or institution, and for the ownership status of a person's or institution's investments.

Trading and financial assets

In derivatives trading or for financial instruments, the concept of a position is used extensively. There are two basic types of position: a long and a short.

Traded options will be used in the following explanations. The same principle applies for futures and other securities. For simplicity, only one contract is being traded in these examples.

Long position