expm1(1.E-10)
powers(x,3)
fromdigits([1,2,3])
qfbredsl2(Qfb(1,7,19))
nfcompositum(nfinit(a^2+1),x^2+a,x^2+a+1)

ellissupersingular(ellinit([1,0],19))
ellisdivisible(ellinit([1,1]),[72,611],3)
ellxn(ellinit([1,1]),3)

fun(x,y,z=0,t=1)=
{
  my(a,b,c);
  ...;
  a;
}
addhelp(fun,"computes the ... of x and y...");

default(strictargs,0);
fun(a,b=1)=[a,b];
fun(2)
fun()
default(strictargs,1);
fun(a,b=1)=[a,b];
fun(2)
fun()

  my(s);
  forprime(p=3,,
    if(p%4==1,s++,
              s--);
    if(s==1,
       return(p))
  );

trans(P)=subst(P,x,x+1)
trans1(P)=subst(P,'x,'x+1)
trans2(P)=my(v=variable(P));subst(P,v,v+1)
trans3(P,x=variable(P))=subst(P,x,x+1)

nome(x)=exp(2*I*Pi*x)
nome1(x)=localprec(precision(x));exp(2*I*Pi*x)
nome2(x,prec=precision(x))=localprec(prec);\
             exp(2*I*Pi*x)

iferr(tan(Pi/2),E,Vec(E))
mytan(x)=iferr(tan(x),E,oo)
mytan(x)=iferr(tan(x),E,oo, #Vec(E)==5 && 
  Vec(E)[1..4]==
   ["e_DOMAIN","tan","argument","=","Pi/2 + kPi"])

rho(n)=
{
  my(x,z);
  x=2; y=5;
  while(gcd(y-x,n)==1,
      x=(x^2+1)%n;
      y=(y^2+1)%n; y=(y^2+1)%n
      );
  gcd(n,y-x)
}