passing a function and then calling the function with parameters

[Joseph Alotta]

Greetings,
I am writing a solving function.   You pass it the name of a function 
and it
calls the functions many times until it finds the value that returns 
zero.  How would
this be set up?

sub plusthree {
#  the function we are solving for
        my ($x) = @_
   return $x + 3;
}
sub solve {
#  the solving routine
   my ($function) = @_;
   ......
        $z = 0;
        # calls passed function with parameter $z
   $a = &{$function}($z);
}
#using solver to solve our function.
$answer = &solve( \&plusthree );
Thank you,
Joe.