Re: Fun Question: Square Root of 5 to 10000 digits

My entry was,

perl -MMath::Pari -e'Math::Pari::setprecision(10000); my $foo = PARI(5
+); my $bar = $foo->sqrt; print $bar,$/,$bar**2,$/'
[download]

which is cheating I suppose. But it's really fast.

After Compline,
Zaxo

Comment on Re: Fun Question: Square Root of 5 to 10000 digits Download Code

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Re^2: Fun Question: Square Root of 5 to 10000 digits by syphilis (Archbishop) on Feb 27, 2007 at 23:26 UTC
You can do essentially the same with Math::MPFR: `perl -MMath::MPFR=:mpfr -e "Rmpfr_set_default_prec(10000); $foo = Math +::MPFR->new(5); $bar = $foo 0.5; print $bar, $/, $bar 2, $/"` [download] With Math::MPFR, setting a default precision of 10000, means you have 10000 bits of precision, not 10000 decimal digits of precision. To be guaranteed 10000 decimal digits of precision I think you need to ask for 33220 bits - ie ceil(10000 / log(2)). I haven't checked whether Math::PARI sets its precision in bits or decimal digits. Cheers, Rob	[reply] [d/l]
Re^3: Fun Question: Square Root of 5 to 10000 digits by zentara (Archbishop) on Feb 28, 2007 at 12:41 UTC
*With Math::MPFR, setting a default precision of 10000, means you have 10000 bits of precision, not 10000 decimal digits of precision.* Doh! You are right, I was wondering last night why I was getting a 1/3 factor of digits. 10000 gave me ~ 3000 decimal places, while 100000 precision gave me ~30000 decimal places. I thought it might be the print accuracy needed to do the inverse, but I was wrong. Thanks for clearly that up. :-) I'm not really a human, but I play one on earth. Cogito ergo sum a bum	[reply]


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