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Some Gallot-inspired sillyness

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  • Phil Carmody
    Two rather silly things. Firstly, after pulling a completely random number out of the air rather than actually remembering the error-bound in Yves initial
    Message 1 of 6 , Jun 20, 2001
      Two rather silly things.


      Firstly, after pulling a completely random number out of the air rather than actually remembering the error-bound in Yves initial 'FFT' mail, I decided to start rechecking a 'Proth' prime that was in fact valid anyway, but using a non-FFT method.
      I now 'proudly' present what I believe to be the world's largest non-FFT-proved prime! (one of David Underbakke's)
      116691*2^337001+1 .
      Certainly a target nearly as sensible as Paul Jobling's faux Titanix prime which was in the most part made from N+/-1 steps rather than EC steps.


      Secondly, I decided to start code-reviewing and verifying some other FFT code used in the prime arena. The particular code I looked at appeared to not suffer from the overflow risk problem! Not only that, but I managed to optimise it too!

      So I also, even more proudly, present what I believe to be the world's smallest C program to print the world's largest prime!

      #define P for(p=t;p<t+N;
      int m=754974721,N,t[1<<22],*p,i,e
      =4625195,j,s,c,U;f(d){for(s=1<<23
      ;s;d=d*1LL*d%m,s/=2)if(s<N)P p+=s
      )for(i=s,c=1;i;i--)j=*p+p[s],p[s]
      =(m+*p-p[s])*1LL*c%m,*p++=j%m,c=c
      *1LL*d%m;for(j=0;++i<N;){for(c=N/
      2;!((j^=c)&c);c/=2);i<j?t[i]^=t[j
      ]^=t[i]^=t[j]:0;}}main(){for(*t=2
      ,U=N=1;e/=2;){U=U*1LL*(m+1)/2%m;N
      *=2;f(362);P)*p++=*p*1LL**p%m*U%m
      ;f(415027540);P)s+=*p<<(e&1),*p++
      =s%10,s/=10;}for(--*t;p>t;)(e|=*
      --p)&&printf("%d",*p);}

      Yes, it's based on Fabrice's Bellard's IOCCC entry from last year. However, it's over 30 bytes (about 7%) shorter.

      (It takes a few minutes to run, and produces >2MB of numeric output.)

      Enjoy,
      Phil


      Mathematics should not have to involve martyrdom;
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    • Christ van Willegen
      ... [SNIP silly thing] ... [SNIP Phil d IOCCC entry] ... You should be disallowed, you know :-) Christ van Willegen
      Message 2 of 6 , Jun 20, 2001
        On 20 Jun 2001, Phil Carmody wrote:
        > Two rather silly things.

        [SNIP silly thing]

        > Secondly, I decided to start code-reviewing and verifying some
        > other FFT code used in the prime arena. The particular code I
        > looked at appeared to not suffer from the overflow risk problem!
        > Not only that, but I managed to optimise it too!
        >
        > So I also, even more proudly, present what I believe to be the
        > world's smallest C program to print the world's largest prime!

        [SNIP Phil'd IOCCC entry]

        > Yes, it's based on Fabrice's Bellard's IOCCC entry from last
        > year. However, it's over 30 bytes (about 7%) shorter.

        You should be disallowed, you know :-)

        Christ van Willegen
      • d.broadhurst@open.ac.uk
        ... ignoring cosmic rays and carmody brain failure (which are both more probable than FFT failure:-)
        Message 3 of 6 , Jun 20, 2001
          Phil Carmody wrote:
          >the world's largest prime!
          ignoring cosmic rays and carmody brain failure
          (which are both more probable than FFT failure:-)
        • Nathan Russell
          On Wed, 20 Jun 2001 17:33:37 +0200 (CEST), Christ van Willegen ... Why? Isn t there a rule that all programs must be in the public domain? :-) Nathan
          Message 4 of 6 , Jun 20, 2001
            On Wed, 20 Jun 2001 17:33:37 +0200 (CEST), Christ van Willegen
            <christw@...> wrote:

            >On 20 Jun 2001, Phil Carmody wrote:
            >> Two rather silly things.
            >
            >[SNIP silly thing]
            >
            >> Secondly, I decided to start code-reviewing and verifying some
            >> other FFT code used in the prime arena. The particular code I
            >> looked at appeared to not suffer from the overflow risk problem!
            >> Not only that, but I managed to optimise it too!
            >>
            >> So I also, even more proudly, present what I believe to be the
            >> world's smallest C program to print the world's largest prime!
            >
            >[SNIP Phil'd IOCCC entry]
            >
            >> Yes, it's based on Fabrice's Bellard's IOCCC entry from last
            >> year. However, it's over 30 bytes (about 7%) shorter.
            >
            >You should be disallowed, you know :-)

            Why? Isn't there a rule that all programs must be in the public
            domain? :-)

            Nathan
          • Christ van Willegen
            On Wed, 20 Jun 2001, Nathan Russell wrote: [SNIP Phil s even more obfuscated IOCCC entry] ... Yes, but Phil does this _every_time_. Some time ago, Phil
            Message 5 of 6 , Jun 20, 2001
              On Wed, 20 Jun 2001, Nathan Russell wrote:

              [SNIP Phil's even more obfuscated IOCCC entry]

              > >You should be disallowed, you know :-)
              >
              > Why? Isn't there a rule that all programs must be in the public
              > domain? :-)
              >
              > Nathan

              Yes, but Phil does this _every_time_.

              Some time ago, Phil contributed an 'illegal' prime into Chris'
              database (he one that, you know, contains the highly illegal
              source to decrypting DVD's. Oh my, now mathematics _itself_ may
              be sued by the MPAA/RIAA if we're not careful). If I remember
              correctly, he got his hands onto the program before turning
              it into a prime, optimizing the code even further. He even
              _admitted_ doing this on the list (I can't find the reference,
              but I know it's there...)

              Before I get flame-mail from all over the planet, all of this
              was :-) for the humor-impaired.

              Phil, thanks for optimizing everything you see!

              (I'll shut up now, I've ranted enough already today)

              Christ van Willegen
            • Phil Carmody
              ... Oh dear, am I becoming predictable? ... It was a different piece of code, one by Charles Hannum, that I shrank. ... Maybe just once I ll turn my hand to
              Message 6 of 6 , Jun 20, 2001
                On Wed, 20 June 2001, Christ van Willegen wrote:
                > Yes, but Phil does this _every_time_.

                Oh dear, am I becoming predictable?

                > Some time ago, Phil contributed an 'illegal' prime into Chris'
                > database (he one that, you know, contains the highly illegal
                > source to decrypting DVD's. Oh my, now mathematics _itself_ may
                > be sued by the MPAA/RIAA if we're not careful). If I remember
                > correctly, he got his hands onto the program before turning
                > it into a prime, optimizing the code even further. He even

                It was a different piece of code, one by Charles Hannum, that I shrank.

                > Phil, thanks for optimizing everything you see!

                Maybe just once I'll turn my hand to something useful.

                Naaaaaah!

                Phil

                Mathematics should not have to involve martyrdom;
                Support Eric Weisstein, see http://mathworld.wolfram.com
                Find the best deals on the web at AltaVista Shopping!
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