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MathGroup Archive 2007

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Re: PrimePi and limit of argument

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77994] Re: PrimePi and limit of argument
  • From: dh <dh at metrohm.ch>
  • Date: Thu, 21 Jun 2007 05:37:47 -0400 (EDT)
  • References: <f58dp5$8np$1@smc.vnet.net>


Hi Robert,

you have a misunderstanding. 64 bit computer means that the bus is 64 

bit wide, it can fetch 64 bits in one go. Number representation however 

is quite another thing. Machine precision (double) is always 64 bit on 

32 or 64 bit computers. You will always get the same result, although 

required times may differ.

hope this helps, Daniel





Robert Pigeon wrote:

> Hello all,

> 

>   I was playing around with the function PrimePi[] and trying different

> arguments. When I tried PrimePi[10^15] I got the error message saying that

> the argument is too large for this implementation. I know that it is a large

> number.! When I use 10^14 as the argument I get an answer, it takes a while

> but I get an answer.

> 

>  I tried this on a PC running Vista Home Premium 64-bit with Mathematica 6.

> Then I tried the same thing under Windows XP 32-bit. There was no

> difference, I got an answer for 10^14 and same error message with 10^15.

> 

>  

> 

> My question is: I thought that with a 64-bit computer I could use larger

> numbers.! Maybe I am misunderstanding something here, so please help me

> understand J

> 

>  

> 

> Thanks,

> 

>  

> 

> Robert 

> 

>  

> 

> Robert Pigeon

> 




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