with(gfun);
with(NumGfun);
prec := 10000;
deq := diffeqtohomdiffeq(holexprtodiffeq(erf(z),y(z)),y(z));
mypi := convert(evalf[prec](Pi),rational,exact);
#ac_eval(deq, y(z), [0, mypi], prec);
ac_eval(deq, y(z), [0, mypi], prec, usebitburst);
evalf[prec](erf(Pi));
