**The Free On-line Dictionary of Computing (18 March 2015):**

floating-point
A number representation consisting
of a mantissa, M, an exponent, E, and a radix (or
"base"). The number represented is M*R^E where R is the
radix.
In science and engineering, exponential notation or
scientific notation uses a radix of ten so, for example, the
number 93,000,000 might be written 9.3 x 10^7 (where ^7 is
superscript 7).
In computer hardware, floating point numbers are usually
represented with a radix of two since the mantissa and
exponent are stored in binary, though many different
representations could be used. The IEEE specify a
standard representation which is used by many hardware
floating-point systems. Non-zero numbers are normalised so
that the binary point is immediately before the most
significant bit of the mantissa. Since the number is
non-zero, this bit must be a one so it need not be stored. A
fixed "bias" is added to the exponent so that positive and
negative exponents can be represented without a sign bit.
Finally, extreme values of exponent (all zeros and all ones)
are used to represent special numbers like zero and positive
and negative infinity.
In programming languages with explicit typing,
floating-point types are introduced with the keyword "float"
or sometimes "double" for a higher precision type.
See also floating-point accelerator, floating-point unit.
Opposite: fixed-point.
(2008-06-13)