default(nbthreads)

default(timer,1);
isprime(2^600+187)
cpu time = 1,244 ms, real time = 197 ms.
nbthreads = default(nbthreads);
default(nbthreads,1)
isprime(2^600+187)
time = 660 ms.
default(nbthreads,nbthreads);

ismersenne(x)=ispseudoprime(2^x-1);
apply(ismersenne,primes(400))
cpu time = 1,248 ms, real time = 1,247 ms.
parapply(ismersenne,primes(400))
cpu time = 2,253 ms, real time = 298 ms.
select(ismersenne,primes(400))
cpu time = 1,192 ms, real time = 1,199 ms.
parselect(ismersenne,primes(400))
cpu time = 2,248 ms, real time = 299 ms.

ismersenne(x)=ispseudoprime(2^x-1);
fun(V)=parvector(#V,i,ismersenne(V[i]));
fun(primes(400))
break
export(ismersenne)
fun(primes(400))

export(f=25);
f
parsum(i=1,1,f)

V=primes(400);
parvector(#V,i,ispseudoprime(2^V[i]-1))
break
exportall()
parvector(#V,i,ispseudoprime(2^V[i]-1))

fun(n)=bnfinit(x^n-2).no;
parapply(fun,[1..30])
break
fun(n)=bnfinit('x^n-2).no;
default(timer,1);
default(parisize,"16M");
apply(fun,[1..30])
cpu time = 5,284 ms, real time = 5,281 ms.
 parapply(fun,[1..30])
cpu time = 9,084 ms, real time = 2,045 ms.
 parapply(fun,-[-30..-1])
cpu time = 9,281 ms, real time = 1,905 ms.

thuemorse(n)= 
 my(V=binary(n)); (-1)^sum(i=1,#V,V[i]);
export(thuemorse);
default(timer,1);
sum(n=1,2*10^6, thuemorse(n)/n*1.)
cpu time = 4,861 ms, real time = 4,862 ms.
parsum(n=1,2*10^6, thuemorse(n)/n*1.)
cpu time = 17,245 ms, real time = 4,426 ms.
parsum(N=1,200, \
  sum(n=1+(N-1)*10^4, N*10^4, thuemorse(n)/n*1.))
cpu time = 11,836 ms, real time = 1,526 ms.

ismersenne(x)=ispseudoprime(2^x-1);
export(ismersenne)
parfor(p=1,999,ismersenne(p),c,if(c,print(p)))
prodmersenne(N)=
  { my(R=1);
    parforprime(p=1,N,
      ismersenne(p),
      c,
      if(c, R*=p));
    R;
  }
prodmersenne(1000)
cpu time = 108 ms, real time = 31 ms.

parforprime(p=1,999,ismersenne(p),c,\
      if(c,print(p)))
prodmersenne(N)=
{ my(R=1);
  parforprime(p=1,N,
    ismersenne(p),
    c,
    if(c, R*=p));
  R;
}
prodmersenne(1000)

parforvec(v=[[1,3],[1,3]],factorback(v)\
            ,f,print(v,":",f))
parploth(x=-4.5,6,\
    intnum(t=0,x,if(t,1/gamma(t))))

ismersenne(x)=ispseudoprime(2^x-1);
export(ismersenne)
findmersenne(a)=
  {
    parforprime(p=a,,ismersenne(p),c,
      if(c,return(p)));
  }
findmersenne(4000)
cpu time = 2,600 ms, real time = 366 ms.
findmersenne(8)
cpu time = 4 ms, real time = 1 ms.
findmersenne(8)

parfirst(fun,V)=
  parfor(i=1,#V,fun(V[i]),j,if(j,return([i,j])));
parfirst(ismersenne,[4001..5000])
cpu time = 3,104 ms, real time = 442 ms.