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Fixed PR 7650.

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iota now uses (+ start (* n step)) to calculate the elements, instead of successive subtractions.

svn: r6025
This commit is contained in:
Jens Axel Soegaard 2007-04-23 19:43:43 +00:00
parent 940d100b2d
commit a5550a69da
1 changed files with 12 additions and 9 deletions
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13
collects/srfi/1/cons.ss
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@ -102,11 +102,14 @@
(check-arg integer? count 'iota) (check-arg integer? count 'iota)
(check-arg number? start 'iota) (check-arg number? start 'iota)
(check-arg number? step 'iota) (check-arg number? step 'iota)
(let ((last-val (+ start (* (- count 1) step)))) (unless (or (zero? count) (positive? count))
(do ((count count (- count 1)) (error 'iota "count expected to be non-negative, got: ~a" count))
(val last-val (- val step)) (let loop ([n 0])
(ans '() (cons val ans))) (cond
((<= count 0) ans))))) [(= n count) '()]
[else (cons (+ start (* n step))
(loop (add1 n)))]))))
) )