http://qs1969.pair.com?node_id=134454

in reply to Help w/ Code Optimization

You might also try this :
```sub Root2 {
my \$num        = shift;
my \$root       = shift;
my \$iterations = shift || 10;
if ( \$root == 0 ) { return 1 }
if ( \$num < 0 ) { return undef }
my \$current = Math::BigFloat->new();
my \$guess   = Math::BigFloat->new( \$num / \$root );
my \$t=Math::BigFloat->new(\$guess**(\$root-1)); 1st version : WRONG ! sh
+ould be in the loop.
for ( 1 .. \$iterations ) {
\$current = \$guess - ( \$guess * \$t - \$num ) / ( \$root * \$t  );
if ( \$guess eq \$current ) { last }
\$t=Math::BigFloat->new(\$current**(\$root-1));
\$guess = \$current;
}
return \$current;
}
The idea behind, is that '**' is MUCH slower than '*', so I exchange 2 '**' for one '**' and 2 '*'
It seems indeed to speed things alot :
(I'm sure your numerous tests will make it sure ;-)
```timethese(10,{
'Root'=> sub {Root(1000,60)},
'Root2'=> sub {Root2(1000,60)}});

gives as result :

Benchmark: timing 10 iterations of Root, Root2...
Root: 104 wallclock secs (104.38 usr + 0.01 sys = 104.39 CPU) @ 0.10/s (n=10)
Root2: 15 wallclock secs (14.75 usr + 0.00 sys = 14.75 CPU) @ 0.68/s (n=10)
Root2: 97 wallclock secs (92.67 usr + 0.16 sys = 92.83 CPU) @ 0.11/s (n=10)

UPDATE :
Corrected my code! I misplaced the \$t calculation outside the loop,
which is wrong beccause \$guess change inside the loop.
As you can see it's no more so fast...