for example, the derivative represents the velocity. The derivative of the
expression for velocity represents acceleration.
Diophantine equation An equation in which solutions have to be whole
numbers or perhaps fractions. Named after the Greek mathematician Diophantus
of Alexandria (c.AD 250).
Discrete A term used in opposition to ‘continuous’. There are gaps between
discrete values, such as the gaps between the whole numbers 1, 2, 3, 4,...
Distribution The range of probabilities of events that occur in an experiment
or situation. For example, the Poisson distribution gives the probabilities of x
occurrences of a rare event happening for each value of x.
Divisor A whole number that divides into another whole number exactly. The
number 2 is a divisor of 6 because 6 ÷ 2 = 3. So 3 is another because 6 ÷ 3 =
2.
Empty set The set with no objects in it. Traditionally denoted by ê, it is a
useful concept in set theory.
Exponent A notation used in arithmetic. Multiplying a number by itself, 5 × 5
is written 5^2 with the exponent 2. The expression 5 × 5 × 5 is written 5^3 , and so
on. The notation may be extended: for example, the number 5½ means the
square root of 5. Equivalent terms are power and index.
Fraction A whole number divided by another, for example 3/7.
Geometry Dealing with the properties of lines, shapes, and spaces, the
subject was formalized in Euclid’s Elements in the third century BC. Geometry
pervades all of mathematics and has now lost its restricted historical meaning.
Greatest common divisor, gcd The gcd of two numbers is the largest
number which divides into both exactly. For example, 6 is the gcd of the two
numbers 18 and 84.
Hexadecimal system A number system of base 16 based on 16 symbols, 0,
1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F. It is widely used in computing.
Hypothesis A tentative statement awaiting either proof or disproof. It has the
same mathematical status as a conjecture.
Imaginary numbers Numbers involving the ‘imaginary’ i = √ –1. They help
form the complex numbers when combined with ordinary (or ‘real’) numbers.
Integration A basic operation in Calculus that measures area. It can be
shown to be the inverse operation of differentiation.
Irrational numbers Numbers which cannot be expressed as a fraction (e.g.
marcin
(Marcin)
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