A few side comments: 
sub middle ($$) {
  my ( $a, $b ) = ( shift, shift );
  return ($a + $b) / 2
}

[download]

Don't pass parameters like that, it's confusing: which shift gets executed first? I'd either use it if only one is involved at a time, and possibly if I have to use the rest of @_ as a whole, or stick with:

my ($n,$m)=@_;

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(I tend not to use $a and $b as general purpose variables even when they wouldn't be error prone because... their use is potentially error prone.)

It's a commonly recommended style to put a semicolon on the last line too.

Oh, and there's no need to use prototypes. Actually many people deprecate them. I find them useful for code and autorefs, but other than that they don't buy you much.

print "SQRT 16:\n",  &sqrt( 16 ), $/, $/;

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&-form of sub call is now obsolete and most likely not to do what you want. Read more about this in perldoc perlsub.

In reply to Re: [Study]: Searching for square roots by blazar
in thread [Study]: Searching for square roots by monsieur_champs

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