## table of contents

FACTOR(1plan9) | FACTOR(1plan9) |

# NAME¶

factor, primes - factor a number, generate large primes

# SYNOPSIS¶

**factor** [ *number* ]

**primes** [ *start* [ *finish* ] ]

# DESCRIPTION¶

*Factor* prints *number* and its prime factors, each
repeated the proper number of times. The number must be positive and less
than 2**54 (about 1.8e16)

If no *number* is given, *factor* reads a stream of
numbers from the standard input and factors them. It exits on any input not
a positive integer. Maximum running time is proportional to sqrt(n).

*Primes* prints the prime numbers ranging from *start*
to *finish*, where *start* and *finish* are positive numbers
less than 2**56. If *finish* is missing, *primes* prints without
end; if *start* is missing, it reads the starting number from the
standard input.

# SOURCE¶

**/src/cmd/factor.c**

**/src/cmd/primes.c**