1 ! Copyright (C) 2008 Doug Coleman, Michael Judge.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: arrays combinators kernel math math.analysis math.functions sequences
4 sequences.lib sorting ;
8 [ sum ] [ length ] bi / ;
10 : geometric-mean ( seq -- n )
11 [ length ] [ product ] bi nth-root ;
13 : harmonic-mean ( seq -- n )
14 [ recip ] sigma recip ;
17 natural-sort dup length even? [
18 [ midpoint@ dup 1- 2array ] keep nths mean
20 [ midpoint@ ] keep nth
31 [ [ mean ] keep [ - sq ] with sigma ] keep
39 [ std ] [ length ] bi sqrt / ;
41 : ((r)) ( mean(x) mean(y) {x} {y} -- (r) )
42 ! finds sigma((xi-mean(x))(yi-mean(y))
43 0 [ [ [ pick ] dip swap - ] bi@ * + ] 2reduce 2nip ;
45 : (r) ( mean(x) mean(y) {x} {y} sx sy -- r )
46 * recip [ [ ((r)) ] keep length 1- / ] dip * ;
48 : [r] ( {{x,y}...} -- mean(x) mean(y) {x} {y} sx sy )
49 first2 [ [ [ mean ] bi@ ] 2keep ] 2keep [ std ] bi@ ;
51 : r ( {{x,y}...} -- r )
54 : r^2 ( {{x,y}...} -- r )
57 : least-squares ( {{x,y}...} -- alpha beta )
58 [r] { [ 2dup ] [ ] [ ] [ ] [ ] } spread
59 ! stack is mean(x) mean(y) mean(x) mean(y) {x} {y} sx sy
60 [ (r) ] 2keep ! stack is mean(x) mean(y) r sx sy
61 swap / * ! stack is mean(x) mean(y) beta