your insights are exactly what I needed. I spotted the type casting of int but I have not thought it constrained all the operations too.. what a complicated world they have with C..

Now I ported to a more perlish versions, but speaking frankly, I'm quite struggling with it's efficiency. Infact the inner for loop for a precision of 1000 cause each of it's line to be called something like 3 million of times if I read correctly the Devel::NYTProf output.

UPDATE some output from NYTProf Performance Profile

Line    Statements    Time on line        Code

 9    1002               49.4ms        for $i(reverse 1..$l){
10    3347682            441ms                $x=10*$a[$i-1]+$q*$i;
11    3347682            474ms                $a[$i-1]=$x%(2*$i-1);
12    3347682            882ms                $q=int($x/(2*$i-1))
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This inner for loop if I read correctly it's not influenced by the outer $j and only set a final (?) $q and the array element $a[$i-1] so i'm trying to cut the loop from there and prebuild an array of q linkable with $j indexes and prefilling the @a accordingly. No big luck until now.

In reality I'm working blindly not having well understood what the code do. I'll try a reverse eng. based on print statements if i do not desist sooner. Another ugly think I've done is the last line where I merely susbtitute the leading 03 with 3, any attempt to do this within the loop failed.

Anyway thank you again!

use strict;
use warnings;

my $n=1002;

my $len = 1 + int (10 * $n / 3);

my $pi;

my @a= (2) x $len;

my $nines = 0;

my $predigit = 0;

foreach my $j(1..$n){
    my $q = 0;
    foreach my $i( reverse 1..$len){
        my $x = 10 * $a[$i-1] + $q * $i;
        $a[$i-1] = $x % (2 * $i - 1);
        $q = int($x / (2 * $i - 1));
    }
    $a[0]=$q%10;
    $q=int($q/10);
    if (9 == $q){ ++$nines;   }
    elsif(10 == $q){
          $pi.=$predigit + 1;
          for (my $k = 0; $k < $nines; $k++){$pi.=0}
          $predigit = $nines = 0;
    }
    else{
         $pi.= int $predigit;
         $predigit = $q;
         if(0 != $nines){
              for (my $k = 0; $k < $nines; $k++) {
                  $pi.=9;
              }
              $nines = 0;
        }
    }
}
print $pi=~s/^03/3./r;
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PS and yes these are the Pi digits and the C source is what you spotted!

L*