Crystal (software)

CRYSTAL is a quantum chemistry ab initio program, designed primarily for calculations on crystals (3 dimensions), slabs (2 dimensions) and polymers (1 dimension) using translational symmetry, but it can also be used for single molecules. It is written by V.R. Saunders, R. Dovesi, C. Roetti, R. Orlando, C.M. Zicovich-Wilson, N.M. Harrison, K. Doll, B. Civalleri, I.J. Bush, Ph. D’Arco, and M. Llunell from Theoretical Chemistry Group at the University of Torino and the Computational Materials Science Group at the Daresbury Laboratory near Warrington in Cheshire, England. The current version is CRYSTAL14, released in June 2014. Earlier versions were CRYSTAL88, CRYSTAL92, CRYSTAL95, CRYSTAL98, CRYSTAL03, CRYSTAL06, and CRYSTAL09.

Features

Hamiltonians

List of companions in Doctor Who spin-offs

This is a list of fictional characters who were companions of the Doctor, in various spin-off media based on the long-running British science fiction television series, Doctor Who.

A

ARC

traveled with the 11th doctor

Alex Campbell

Alex is the Doctor's great grandson (the son of Susan Campbell) and features in the Eighth Doctor adventures. He is portrayed by Jake McGann.

He is initially wary of the Doctor due to the xenophobic atmosphere on Earth following the Dalek occupation. Despite this, he eventually accepts the Doctor but while he is impressed by the technology of the TARDIS he chooses not to travel with him as he wants to become an architect.

During the second Dalek invasion in the plays Lucie Miller and To The Death, Alex becomes a leader for the human resistance on Earth. He sacrifices himself to allow Lucie and Susan the opportunity to thwart the Dalek's plan.

Amy

Amy, portrayed by Ciara Janson, is a companion of the Fifth Doctor in the Key 2 Time series, which includes the plays The Judgement of Isskar, The Destroyer of Delights and The Chaos Pool.

Crystal (given name)

Crystal /ˈkrɪstəl/ is a common female given name. Variant forms of the name include Kristal, Krystal, Cristal, Krystle and Kristol.

It is a 19th-century coinage, derived from crystal, a transparent quartz gemstone, usually colorless, that can be cut to reflect brilliant light, whose name comes from Ancient Greek κρύσταλλος krystallos "ice". The Greek variant of the name is Crystallia or Krystallia (Κρυσταλλία). The TV series Dynasty made the name famous in the 1980s with a character named Krystle. Chrystal, a variant spelling, was probably influenced by Greek χρυσός khrusos "gold".

People

Factorial

In mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example,

The value of 0! is 1, according to the convention for an empty product.

The factorial operation is encountered in many areas of mathematics, notably in combinatorics, algebra, and mathematical analysis. Its most basic occurrence is the fact that there are n! ways to arrange n distinct objects into a sequence (i.e., permutations of the set of objects). This fact was known at least as early as the 12th century, to Indian scholars.Fabian Stedman in 1677 described factorials as applied to change ringing. After describing a recursive approach, Stedman gives a statement of a factorial (using the language of the original):

Now the nature of these methods is such, that the changes on one number comprehends [includes] the changes on all lesser numbers, ... insomuch that a compleat Peal of changes on one number seemeth to be formed by uniting of the compleat Peals on all lesser numbers into one entire body;

Mathematics

Mathematics (from Greek μάθημα máthēma, “knowledge, study, learning”) is the study of topics such as quantity (numbers),structure,space, and change. There is a range of views among mathematicians and philosophers as to the exact scope and definition of mathematics.

Mathematicians seek out patterns and use them to formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proof. When mathematical structures are good models of real phenomena, then mathematical reasoning can provide insight or predictions about nature. Through the use of abstraction and logic, mathematics developed from counting, calculation, measurement, and the systematic study of the shapes and motions of physical objects. Practical mathematics has been a human activity for as far back as written records exist. The research required to solve mathematical problems can take years or even centuries of sustained inquiry.

Rigorous arguments first appeared in Greek mathematics, most notably in Euclid's Elements. Since the pioneering work of Giuseppe Peano (1858–1932), David Hilbert (1862–1943), and others on axiomatic systems in the late 19th century, it has become customary to view mathematical research as establishing truth by rigorous deduction from appropriately chosen axioms and definitions. Mathematics developed at a relatively slow pace until the Renaissance, when mathematical innovations interacting with new scientific discoveries led to a rapid increase in the rate of mathematical discovery that has continued to the present day.

Math (disambiguation)

Math (or Maths in most English-speaking countries) is used colloquially to refer to mathematics.

Math may also refer to:

See also