projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 62c1033b RM |
1 | .TH FACTOR 1 |
| 2 | .SH NAME | |
| 3 | factor, primes \- factor a number, generate large primes | |
| 4 | .SH SYNOPSIS | |
| 5 | .B factor | |
| 6 | [ number ] | |
| 7 | .PP | |
| 8 | .B primes | |
| 9 | .SH DESCRIPTION | |
| 10 | When | |
| 11 | .I factor | |
| 12 | is invoked without an argument, it waits for a number to be typed in. | |
| 13 | If you type in a positive | |
| 14 | number less than 2\u\s756\s0\d (about | |
| 15 | .if n 7.2e16) | |
| 16 | .if t 7.2\(mu10\u\s716\s0\d\|) | |
| 17 | it will factor the number and print its prime factors; each one is printed | |
| 18 | the proper number of times. | |
| 19 | Then it waits for another number. | |
| 20 | It exits if it encounters a zero or any non-numeric character. | |
| 21 | .PP | |
| 22 | If | |
| 23 | .I factor | |
| 24 | is invoked with an argument, it factors the number | |
| 25 | as above and then exits. | |
| 26 | .PP | |
| 27 | Maximum time to factor is proportional to | |
| 28 | .if n sqrt(n) | |
| 29 | .if t \(sr\o'\fIn\fR\(rn' | |
| 30 | and occurs when | |
| 31 | .I n | |
| 32 | is prime | |
| 33 | or the square of a prime. | |
| 34 | It takes 1 minute to factor a prime | |
| 35 | near | |
| 36 | 10\u\s714\s0\d | |
| 37 | on a PDP11. | |
| 38 | .PP | |
| 39 | When | |
| 40 | .I primes | |
| 41 | is invoked, it waits for a number to be typed in. | |
| 42 | If you type in a positive | |
| 43 | number less than 2\u\s756\s0\d | |
| 44 | it will print all primes greater than or | |
| 45 | equal to this number. | |
| 46 | .SH DIAGNOSTICS | |
| 47 | `Ouch.' for input out of range or for garbage input. |