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Re: Re: Prime Number Finder

by Anonymous Monk
on May 04, 2002 at 18:08 UTC ( #164038=note: print w/replies, xml ) Need Help??

in reply to Re: Prime Number Finder
in thread Prime Number Finder

Isn't the math wrong here? I get false primes with this.

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Re: Re: Re: Prime Number Finder
by LanceDeeply (Chaplain) on Jul 17, 2002 at 19:58 UTC
    nope! they all look prime to me!
    i like it, i'm gonna use it to explain programming loops to a mathmatician friend. i took the liberty to re-arrange a touch...
    sub isPrime { my $number = shift; my $sqrt = sqrt $number; my $d = 2; while (1) { return 0 if ( $number % $d == 0 ); return 1 if ( $d > $sqrt ); $d++; } }
Re^3: Prime Number Finder
by Anonymous Monk on Apr 16, 2013 at 20:44 UTC
    In fact, you're right, because numbers which only can be devided in 1, themselves and their square root will be marked as prime in this way. make the < into a <= and it is solved.

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