Beefy Boxes and Bandwidth Generously Provided by pair Networks
"be consistent"
 
PerlMonks  

Re: Mathematics ethics

by dada (Chaplain)
on Oct 28, 2002 at 15:12 UTC ( #208520=note: print w/replies, xml ) Need Help??


in reply to Mathematics ethics

it took me quite a lot to understand that you were talking about narcissistic numbers (thanks Thelonius!).

that said, your script does not work. the while loop should look like:

while ( $vlnum > 0 ) { $vldig = $vlnum % 10; $vlsum = $vlsum + ($vldig * $vldig * $vldig); $vlnum = $vlnum / 10; }
as for simplicity, I would do it like this:
#!/usr/bin/perl -w use strict; my $vlnum = 0; my $vlsum = 0; print "Insert a number: "; chomp ( $vlnum = <STDIN> ); # map { $vlsum += $_ ** 3 } split //, $vlnum; # oops, this should be (thanks [broquaint]!): $vlsum += $_ ** 3 for split //, $vlnum; if ( $vlsum == $vlnum ) { print "Is narc dude!"; } else { print "Try another number!"; }
cheers,
Aldo

King of Laziness, Wizard of Impatience, Lord of Hubris

Replies are listed 'Best First'.
Re: Re: Mathematics ethics
by RMGir (Prior) on Oct 28, 2002 at 16:00 UTC
    Hmmm, If you're really going for narcissistic numbers as defined by that link, shouldn't the power be the length of the number, instead of 3?

    And in that case, there's a nice complete list available as a link from that page, so you can just do it by table lookups.

    #!/usr/bin/perl -w # Silly super-efficient interactive narcissistic checker... use strict; # http://mathworld.wolfram.com/packages/Narcissistic.dat my %narcs=map {$_ => 1} ( 0,1,2,3,4,5,6,7,8,9,153,370,371,407,1634,8208,9474,54748,92727,93084, 548834,1741725,4210818,9800817,9926315,24678050,24678051,88593477, 146511208,472335975,534494836,912985153,4679307774,32164049650, 32164049651,40028394225,42678290603,44708635679,49388550606, 82693916578,94204591914,28116440335967,4338281769391370, 4338281769391371,21897142587612075,35641594208964132,35875699062250035 +, 1517841543307505039,3289582984443187032,4498128791164624869, 4929273885928088826,63105425988599693916,128468643043731391252, 449177399146038697307,21887696841122916288858,27879694893054074471405, 27907865009977052567814,28361281321319229463398, 35452590104031691935943,174088005938065293023722, 188451485447897896036875,239313664430041569350093, 1550475334214501539088894,1553242162893771850669378, 3706907995955475988644380,3706907995955475988644381, 4422095118095899619457938,121204998563613372405438066, 121270696006801314328439376,128851796696487777842012787, 174650464499531377631639254,177265453171792792366489765, 14607640612971980372614873089,19008174136254279995012734740, 19008174136254279995012734741,23866716435523975980390369295, 1145037275765491025924292050346,1927890457142960697580636236639, 2309092682616190307509695338915,17333509997782249308725103962772, 186709961001538790100634132976990,186709961001538790100634132976991, 1122763285329372541592822900204593,12639369517103790328947807201478392 +, 12679937780272278566303885594196922, 1219167219625434121569735803609966019, 12815792078366059955099770545296129367, 115132219018763992565095597973971522400, 115132219018763992565095597973971522401); while(<>) { chomp; if(exists $narcs{$_}) { print "Is narc, dude\n"; } else { print "Not narc, please try again\n"; } }

    But if it's really numbers equal to the sum of their digits ** 3, then I'm not sure what the exhaustive list would look like...

    I think there WOULD be one, though, since 9**3 is only 729, so that limits how big your number could be. So you could still precompute the possible answers, if you needed an efficient way to answer this question...

    Hehe, it doesn't seem to be a problem that cries out for optimization, does it? :)
    --
    Mike

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://208520]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others meditating upon the Monastery: (2)
As of 2022-05-21 07:12 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    Do you prefer to work remotely?



    Results (76 votes). Check out past polls.

    Notices?