In control engineering, a state space representation is a mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations. To abstract from the number of inputs, outputs and states, the variables are expressed as vectors. Additionally, if the dynamical system is linear and time invariant, the differential and algebraic equations may be written in matrix form. The state space representation (also known as the "time-domain approach") provides a convenient and compact way to model and analyze systems with multiple inputs and outputs. With Failed to parse (Missing texvc executable; please see math/README to configure.): p

The internal state variables are the smallest possible subset of system variables that can represent the entire state of the system at any given time. The minimum number of state variables required to represent a given system, Failed to parse (Missing texvc executable; please see math/README to configure.): n , is usually equal to the order of the system's defining differential equation. If the system is represented in transfer function form, the minimum number of state variables is equal to the order of the transfer function's denominator after it has been reduced to a proper fraction. It is important to understand that converting a state space realization to a transfer function form may lose some internal information about the system, and may provide a description of a system which is stable, when the state-space realization is unstable at certain points. In electric circuits, the number of state variables is often, though not always, the same as the number of energy storage elements in the circuit such as capacitors and inductors. The state variables defined must be linearly independent; no state variable can be written as a linear combination of the other state variables or the system will not be able to be solved.^{[citation needed]}

State commonly refers to either the present condition of a system or entity, or to a governed entity (such as a country) or sub-entity (such as a province or region).

In computer programming, a widget (or control) is an element of a graphical user interface (GUI) that displays an information arrangement changeable by the user, such as a window or a text box. The defining characteristic of a widget is to provide a single interaction point for the direct manipulation of a given kind of data. In other words, widgets are basic visual building blocks which, combined in an application, hold all the data processed by the application and the available interactions on this data.

A family of common reusable widgets has evolved for holding general information based on the Palo Alto Research Center Inc. research for the Xerox Alto User Interface. Different implementations of these generic widgets are often packaged together in widget toolkits, which programmers use to build graphical user interfaces (GUIs). Most operating systems include a set of ready-to-tailor widgets that a programmer can incorporate in an application, specifying how it is to behave. Each type of widgets generally is defined as a class by object-oriented programming (OOP). Therefore, many widgets are derived from class inheritance.

Riek Machar Teny Dhurgon (born 1953), is the first vice-president of the independent Republic of South Sudan.

Riek Machar obtained a PhD in mechanical engineering in 1984 and then joined the rebel Sudan People's Liberation Movement/Army (SPLM/A) during the Second Sudanese Civil War (1983–2005). Riek fell out with the SPLM/A leader John Garang in 1991 and formed a splinter group, the SPLM/A-Nasir. In 1997 Riek made a treaty with the Government of Sudan and become head of the government-backed South Sudan Defense Force (SSDF). In 2000 he left the SSDF and formed a new militia, the Sudan People's Democratic Forces (SPDF), and in 2002 rejoined the SPLA as a senior commander. After the death of John Garang in July 2005, Riek Machar became vice-president of the autonomous Southern Sudan. He became vice-president of South Sudan on 9 July 2011 when the country became independent.

Riek Machar Teny Dhurgon was born in Leer, Unity State in 1953, the 26th son of the chief of both Ayod and Leer. He was brought up as a member of the Presbyterian church. Riek belongs to the Dok section of the Nuer people. He trained as an Engineer at Khartoum University, and obtained a PhD in Philosophy and strategic planning from the University of Bradford in 1984.

William "Bill" Maher, Jr. ( /ˈmɑːr/; born January 20, 1956) is an American stand-up comedian, television host, political commentator, author, and actor. Before his current role as the host of HBO's Real Time with Bill Maher, Maher hosted a similar late-night talk show called Politically Incorrect originally on Comedy Central and later on ABC.

Maher is known for his political satire and sociopolitical commentary, which targets a wide swath of topics including religion, politics, bureaucracies of many kinds, political correctness, the mass media, greed among people and persons in positions of high political and social power, and the lack of intellectual curiosity in the electorate. He supports the legalization of marijuana and same-sex marriage, and serves on the board of PETA. He is also a critic of religion and is an advisory board member of Project Reason, a foundation to promote scientific knowledge and secular values within society. In 2005, Maher ranked at number 38 on Comedy Central's 100 greatest stand-up comedians of all time. Bill Maher received a Hollywood Walk of Fame star on September 14, 2010.