.TH FACTOR 1 .SH NAME factor, primes \- factor a number, generate large primes .SH SYNOPSIS .B factor [ number ] .PP .B primes .SH DESCRIPTION When .I factor is invoked without an argument, it waits for a number to be typed in. If you type in a positive number less than 2\u\s756\s0\d (about .if n 7.2e16) .if t 7.2\(mu10\u\s716\s0\d\|) it will factor the number and print its prime factors; each one is printed the proper number of times. Then it waits for another number. It exits if it encounters a zero or any non-numeric character. .PP If .I factor is invoked with an argument, it factors the number as above and then exits. .PP Maximum time to factor is proportional to .if n sqrt(n) .if t \(sr\o'\fIn\fR\(rn' and occurs when .I n is prime or the square of a prime. It takes 1 minute to factor a prime near 10\u\s714\s0\d on a PDP11. .PP When .I primes is invoked, it waits for a number to be typed in. If you type in a positive number less than 2\u\s756\s0\d it will print all primes greater than or equal to this number. .SH DIAGNOSTICS `Ouch.' for input out of range or for garbage input.