Re: Mathematica slows down

*To*: mathgroup at smc.vnet.net*Subject*: [mg52964] Re: [mg52956] Mathematica slows down*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sat, 18 Dec 2004 03:59:37 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

I don't know what changes; however, you can speed it up by avoiding repeated calls of Prime for the same values NumP=15000; Table[pk[n]=Prime[n],{n,NumP}]; For[k=1,k<NumP,k++, Gap[1]=pk[k+1]-pk[k]; Gap[2]=pk[k+2]-2pk[k+1]+pk[k]; Gap[3]=pk[k+3]-3pk[k+2]+3pk[k+1]-pk[k]; Gap[4]=pk[k+4]-4pk[k+3]+6pk[k+2]-4pk[k+1]+pk[k]; If[Mod[k,1000]==0,Print[k]]] Bob Hanlon > > From: George Szpiro <george at netvision.net.il> To: mathgroup at smc.vnet.net > Date: 2004/12/17 Fri AM 05:20:43 EST > To: mathgroup at smc.vnet.net > Subject: [mg52964] [mg52956] Mathematica slows down > > Hello, > > the following program runs ok for the first 6,000 iterations, then slows > down considerably, and then seems to speed up again after 10,000. Does > anyone know what is going on? > > Thanks, > George > > > NumP=15000; > > For[k=1,k<NumP,k++, > > Gap[1]=Prime[k+1]-Prime[k]; > Gap[2]=Prime[k+2]-2Prime[k+1]+Prime[k]; > Gap[3]=Prime[k+3]-3Prime[k+2]+3Prime[k+1]-Prime[k]; > Gap[4]=Prime[k+4]-4Prime[k+3]+6Prime[k+2]-4Prime[k+1]+Prime[k]; > > If[Mod[k,1000]==0, Print[ k]] > > > ] > > >

**Follow-Ups**:**Re: Re: Mathematica slows down***From:*DrBob <drbob@bigfoot.com>