Special factorials: Difference between revisions
Make note about rf(1); update Factor program and output accordingly.
(→{{header|Wren}}: More efficient.) |
(Make note about rf(1); update Factor program and output accordingly.) |
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* Show rf(119). The result should be undefined.
<br />
;Notes
: Since the factorial inverse of '''1''' is both 0 and 1, your function should return '''0''' in this case since it is normal to use the first match found in a series.
<br />
;See also
* [[Factorial]]
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<lang factor>USING: formatting io kernel math math.factorials math.functions
math.parser math.ranges prettyprint sequences sequences.extras ;
IN: rosetta-code.special-factorials
: sf ( n -- m ) [1..b] [ n! ] map-product ;
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: $ ( n -- m ) [1..b] [ ] [ swap ^ ] map-reduce ;
: (rf) ( n -- m )
[ 1 1 ] dip [ dup reach > ]
[ [ 1 + [ * ] keep ] dip ] while swapd = swap and ;
: rf ( n -- m ) dup 1 = [ drop 0 ] [ (rf) ] if ;
: .show ( n quot -- )
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5 [ $ ] .show nl
"Number of digits in
5 $ log10 >integer 1 + . nl
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0 1 2 9 262144
Number of digits in
183231
rf(1) =
rf(2) = 2
rf(6) = 3
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