21577[PrimeNumbers] Re: Nth Index of a Prime
- Jul 13 9:01 AMDavid Broadhurst wrote:
> David Baugh <PbtoAu@...> wrote:I don't know what David Baugh uses but there is something better.
>> pi(1357911131197531) = 40159216312772
>> The next one is too big for my implementation
> How did you compute pi(x) with x > 10^15, please, David?
At http://mersenneforum.org/showthread.php?t=13210 I wrote:
"Two years ago I searched for a good pi(x) program, found an old mention
of Christian Bau and dug up a link to http://www.cbau.freeserve.co.uk
The link was and still is dead but the Wayback Machine has archived
versions up to 2005 at
There is C++ source by Christian Bau for the Extended Meissel-Lehmer
algorithm. It works to 2^64 and my test runs agree with published counts
by Tomás Oliveira e Silva. I have used the program for a few projects
such as http://primes.utm.edu/curios/includes/puzzio.php. The archive has
Version 0.92, 25/Sep/2003. The site speaks of unfinished work in
progress and mentions future improved versions but I have not found that."
It takes 1 minute for the program to compute pi(1357911131197531) on
one core of a 2.4 GHz Core 2 Duo. The value agrees with David Baugh.
Jens Kruse Andersen
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