gistfile1.txt

needs decimal'
with decimal'
: sqr ( n-n ) dup * ;
3 elements i j sum
1 !i 1 !j 0 !sum
8 !scale
: // ( nn-n ) push 100000000 * pop / ;
: pi_series ( -) repeat @j @i // @sum + !sum 4 @sum * yield @i 2 + !i @j -1 * !j again ;

3 elements s0 s1 s2
: term1 @s2 @s1 - ;
: term2 @s0 @s1 2 * - @s2 + ;
: term3 term1 sqr ;
: term4 term3 term2 // ;
: term5 @s2 term4 - ;
: euler_accelerator pi_series !s0 pi_series !s1 pi_series !s2
  repeat term5 yield pi_series @s2 @s1 !s0 !s1 !s2 again ;
10 [ euler_accelerator putn ', putc space ] times