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 254 (about 1.8×1016).

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 ­√n
‾.

­Primes prints the prime numbers ranging from ­start to finish, where ­start and ­finish are positive numbers less than 256.  If ­finish is missing, ­primes prints without end; if ­start is missing, it reads the starting number from the standard input. 

SOURCE

­/sys/src/cmd/factor.c
­/sys/src/cmd/primes.c

Plan 9  —  May 09, 2000