factor, primes - factor a number, generate large primes
If no arguments are provided on the command line, waits for a number to
be typed in. If a positive number is typed, it factors the number and
print its prime factors; each one is printed the proper number of
times. It then waits for another number. exits if it encounters a
zero or any non-numeric character.
If an argument is provided on the command line, factors the number as
above, then exits.
Maximum time to factor is proportional to sqrt(n) and occurs when n is
prime or the square of a prime.
The largest number that can be dealt with by is 1.0e14.
prints prime numbers between a lower and upper bound. If no arguments
are provided on the command line, waits for two numbers to be typed in.
The first number is interpreted as the lower bound; the second as the
upper bound. All prime numbers in the resulting inclusive range are
If start is specified, all primes greater than or equal to start are
printed. If both start and stop are given, all primes occurring in the
inclusive range start through stop are printed.
start and stop values must be integers represented as long integers.
If the stop value is omitted in either case, runs either until overflow
occurs or until it is stopped by typing the interrupt character.
The largest number that can be dealt with by is 2,147,483,647.
Both commands print when the input is out of range, illegal characters
are encountered, or when start is greater than stop.
Print the prime factorization for the number 12:
Print all prime numbers between 0 and 20: