…
►
►The set of
machine numbers
is the union of
and the set
…
►The lower and upper bounds for the absolute values of the nonzero
machine numbers are given by
…
►
Rounding
…
►Interval arithmetic is intended for bounding the total effect of rounding errors of calculations with
machine numbers.
…
§27.15 Chinese Remainder Theorem
…
►This theorem is employed to increase efficiency in calculating with large
numbers by making use of smaller
numbers in most of the calculation.
…Their product
has 20 digits, twice the
number of digits in the data.
…
►Even though the lengthy calculation is repeated four times, once for each modulus, most of it only uses five-digit integers and is accomplished quickly without overwhelming the
machine’s memory.
Details of a
machine program describing the method together with typical numerical results can be found in
Newman (1967).
…
§27.16 Cryptography
…
►The primes are kept secret but their product
, an 800-digit
number, is made public.
…With the most efficient computer techniques devised to date (2010), factoring an 800-digit
number may require billions of years on a single computer.
For this reason, the codes are considered unbreakable, at least with the current state of knowledge on factoring large
numbers.
…
►If
and
are known,
and
can be determined (mod
) by straightforward calculations that require only a few minutes of
machine time.
…