Re^2: Fun Question: Square Root of 5 to 10000 digits

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, $/"
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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

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Re^3: Fun Question: Square Root of 5 to 10000 digits by zentara (Cardinal) 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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Re^3: Fun Question: Square Root of 5 to 10000 digits
by zentara (Cardinal) 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

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