FACTOR(6)

NAME
factor - factor a number

SYNOPSIS
factor [-hx] [number ...]

DESCRIPTION
The factor utility factors integers larger than 0. When a number is factored, it is printed, followed by a “”:, and the list of (prime) factors on a single line. Factors are listed in ascending order, and are preceded by a space. By default, if a factor divides a value more than once, it will be printed more than once.

When factor is invoked with one or more number arguments, each argument will be factored.

When factor is invoked with no number arguments, factor reads numbers, one per line, from standard input, until end of file or error. Leading white-space and empty lines are ignored. Numbers may be preceded by a single +. Numbers that start with 0x are interpreted as hexadecimal. A 0 input exits the program. Negative numbers are not allowed. Numbers are terminated by a non-digit character (such as a newline). After a number is read, it is factored. Input lines must not be longer than LINE_MAX - 1 (currently 2047) characters.

By default, factor is compiled against the OpenSSL bignum implementation openssl_bn(3), which lets it handle arbitrarily large values. (Note however that very large values can take a very long time to factor.) If factor is compiled without OpenSSL it is limited to the maximum value of unsigned long.

The following option is available:

-h  If the -h flag is specified, factors will be printed in "human-readable" format. If a factor x divides a value n (>1) times, it will appear as x^n.

-x  If the -x flag is specified, factors will be printed in hexadecimal format.

DIAGNOSTICS
Out of range or invalid input results in an appropriate error message to standard error.

AUTHORS
Originally by Landon Curt Noll.