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| (programming, mathematics) | 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.
See also floating-point accelerator, floating-point unit.
Opposite: fixed-point. | |
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