diff options
Diffstat (limited to 'factor.scm')
| -rw-r--r-- | factor.scm | 39 |
1 files changed, 18 insertions, 21 deletions
@@ -8,7 +8,7 @@ ;1. Any copy made of this software must include this copyright notice ;in full. ; -;2. I have made no warrantee or representation that the operation of +;2. I have made no warranty or representation that the operation of ;this software will be error-free, and I am under no obligation to ;provide any services, by way of maintenance, update, or otherwise. ; @@ -17,7 +17,6 @@ ;promotional, or sales literature without prior written consent in ;each case. -(require 'common-list-functions) (require 'modular) (require 'random) (require 'byte) @@ -82,8 +81,10 @@ (if (positive? i) #f #t)))) ;;; prime:products are products of small primes. +;;; was (comlist:notevery (lambda (prd) (= 1 (gcd n prd))) comps)) (define (primes-gcd? n comps) - (comlist:notevery (lambda (prd) (= 1 (gcd n prd))) comps)) + (not (let mapf ((lst comps)) + (or (null? lst) (and (= 1 (gcd n (car lst))) (mapf (cdr lst))))))) (define prime:prime-sqr 121) (define prime:products '(105)) (define prime:sieve (bytes 0 0 1 1 0 1 0 1 0 0 0)) @@ -122,40 +123,37 @@ ;;There is a slight chance @code{(expt 2 (- prime:trials))} that a ;;composite will return @code{#t}. (define prime? prime:prime?) -(define probably-prime? prime:prime?) ;legacy (define (prime:prime< start) (do ((nbr (+ -1 start) (+ -1 nbr))) ((or (negative? nbr) (prime:prime? nbr)) (if (negative? nbr) #f nbr)))) -(define (prime:primes< start count) +;;@body +;;Returns a list of the first @2 prime numbers less than +;;@1. If there are fewer than @var{count} prime numbers +;;less than @var{start}, then the returned list will have fewer than +;;@var{start} elements. +(define (primes< start count) (do ((cnt (+ -2 count) (+ -1 cnt)) (lst '() (cons prime lst)) (prime (prime:prime< start) (prime:prime< prime))) ((or (not prime) (negative? cnt)) (if prime (cons prime lst) lst)))) -;;@args start count -;;Returns a list of the first @2 prime numbers less than -;;@1. If there are fewer than @var{count} prime numbers -;;less than @var{start}, then the returned list will have fewer than -;;@var{start} elements. -(define primes< prime:primes<) (define (prime:prime> start) (do ((nbr (+ 1 start) (+ 1 nbr))) ((prime:prime? nbr) nbr))) -(define (prime:primes> start count) +;;@body +;;Returns a list of the first @2 prime numbers greater than @1. +(define (primes> start count) (set! start (max 0 start)) (do ((cnt (+ -2 count) (+ -1 cnt)) (lst '() (cons prime lst)) (prime (prime:prime> start) (prime:prime> prime))) ((negative? cnt) (reverse (cons prime lst))))) -;;@args start count -;;Returns a list of the first @2 prime numbers greater than @1. -(define primes> prime:primes>) ;;;;Lankinen's recursive factoring algorithm: ;From: ld231782@longs.LANCE.ColoState.EDU (L. Detweiler) @@ -232,14 +230,13 @@ '() (prime:fo m)))) -(define (prime:factor k) +;;@body +;;Returns a list of the prime factors of @1. The order of the +;;factors is unspecified. In order to obtain a sorted list do +;;@code{(sort! (factor @var{k}) <)}. +(define (factor k) (case k ((-1 0 1) (list k)) (else (if (negative? k) (cons -1 (prime:fe (- k))) (prime:fe k))))) -;;@args k -;;Returns a list of the prime factors of @1. The order of the -;;factors is unspecified. In order to obtain a sorted list do -;;@code{(sort! (factor @var{k}) <)}. -(define factor prime:factor) |