Re: Is short-circuit evaluation possible with parfor() ?

[hermann@stamm-wilbrandt.de]

On 2026-02-10 14:51, Ruud H.G. van Tol wrote:
> Sure, but cleaning up for 192 threads, just takes a bit more time than
> for half of that, etc.
but running with have the number of threads takes double the time, but I 
see your point.

> > Proving BIG numbers prime can earn you 150,000 USD price money ;-)
> > https://www.eff.org/awards/coop
>
> Good luck!
I used isok3() to plot the primes (#s) of prime(n)#/prime(i)+1 with GP. 
The last row #s correspond to primes of 100 digits. The 100K digit 
primes I mentioned are a factor 1,000 bigger. And another factor 1,000 
on those give the 150,000 USD ;-)

In case not proving prime mathematically I bought 8x AMD Instinct MI50 
GPUs with a measured total peak of 50 TFLOPs FP64 (around 100€ used on 
ebay). One of them can test a 100 million decimal digit Mersenne number 
for being prime in less than 10 days ...


Here the GP primorial prime art:

? 
pdivisors(n)={L=List();;my(p=prime(n+1)#);parfor(i=2,n+1,ispseudoprime(1+p/prime(i)),r,if(r,listput(~L,i)););L};
? 
for(j=1,54,S=Set(pdivisors(j));print1(".");for(i=2,j+1,print1(if(vecsearch(S,i)!=0,"# 
","  ")));print("."));
.# .
.# # .
.# # # .
.  # # # .
.  #   # # .
.  # # #     .
.# #           .
.        # #     .
.# #         #     .
.          # # # #   .
.    #       # #   # # .
.      # #               .
.              #           .
.    #   #         #         .
.    #                     #   .
.        # #   #                 .
.          #                       .
.                                    .
.              #                       .
.                          #             .
.                #   #             # #     .
.  #   #                         # #   #     .
.                                              .
.                                                .
.                  #                       #       .
.                                    #               .
.                  #                                   .
.      #                                       # #       .
.                      #                               #   .
.              #                                             .
.  #                         #         #                       .
.                                                                .
.                    #                   #               #         .
.                                              #                     .
.                                  #                                   .
.      #                         #                                       
.
.    #                                                       #           
  .
.                      #                 # #       #             #       
#   .
.                        #               #                               
      .
.                #                   # #                     #           
        .
.                                #                                       
          .
.      # #   #           #                                               
            .
.                                                                    #   
# #     #     .
.                                            #   #                       
#               .
.                # #                 #                                   
            #     .
.      #                               #                                 
#                   .
.                                          #                         #   
                      .
.                          #       #               #                     
              #         .
.                        #                                               
                          .
.                                                                        
                            .
.                                                                        
# # #                         .
.          #       #                       #                             
                                .
.          #               #                                             
                          #       .
.      #         # #                   #                                 
                                    .
?


Regards,

Hermann.