$t     = countit( $fort, $code );
	$title = "timethis for $fort" unless defined $title;
	$forn  = $t->[-1];
    }
    local $| = 1;
    $style = "" unless defined $style;
    printf("%10s: ", $title) unless $style eq 'none';
    print timestr($t, $style, $Default_Format),"\n" unless $style eq 'none';

    $n = $forn if defined $forn;

    # A conservative warning to spot very silly tests.
    # Don't assume that your benchmark is ok simply because
    # you don't get this warning!
    print "            (warning: too few iterations for a reliable count)\n"
	if     $n < $Min_Count
	    || ($t->real < 1 && $n < 1000)
	    || $t->cpu_a < $Min_CPU;
    $t;
}


$_Usage{timethese} = <<'USAGE';
usage: timethese($count, { Name1 => 'code1', ... });        or
       timethese($count, { Name1 => sub { code1 }, ... });
USAGE

sub timethese{
    my($n, $alt, $style) = @_;
    die usage unless ref $alt eq 'HASH';

    my @names = sort keys %$alt;
    $style = "" unless defined $style;
    print "Benchmark: " unless $style eq 'none';
    if ( $n > 0 ) {
	croak "non-integer loopcount $n, stopped" if int($n)<$n;
	print "timing $n iterations of" unless $style eq 'none';
    } else {
	print "running" unless $style eq 'none';
    }
    print " ", join(', ',@names) unless $style eq 'none';
    unless ( $n > 0 ) {
	my $for = n_to_for( $n );
	print ", each" if $n > 1 && $style ne 'none';
	print " for at least $for CPU seconds" unless $style eq 'none';
    }
    print "...\n" unless $style eq 'none';

    # we could save the results in an array and produce a summary here
    # sum, min, max, avg etc etc
    my %results;
    foreach my $name (@names) {
        $results{$name} = timethis ($n, $alt -> {$name}, $name, $style);
    }

    return \%results;
}


$_Usage{cmpthese} = <<'USAGE';
usage: cmpthese($count, { Name1 => 'code1', ... });        or
       cmpthese($count, { Name1 => sub { code1 }, ... });  or
       cmpthese($result, $style);
USAGE

sub cmpthese{
    my ($results, $style);

    if( ref $_[0] ) {
        ($results, $style) = @_;
    }
    else {
        my($count, $code) = @_[0,1];
        $style = $_[2] if defined $_[2];

        die usage unless ref $code eq 'HASH';

        $results = timethese($count, $code, ($style || "none"));
    }

    $style = "" unless defined $style;

    # Flatten in to an array of arrays with the name as the first field
    my @vals = map{ [ $_, @{$results->{$_}} ] } keys %$results;

    for (@vals) {
	# The epsilon fudge here is to prevent div by 0.  Since clock
	# resolutions are much larger, it's below the noise floor.
	my $rate = $_->[6] / (( $style eq 'nop' ? $_->[4] + $_->[5]
						: $_->[2] + $_->[3]) + 0.000000000000001 );
	$_->[7] = $rate;
    }

    # Sort by rate
    @vals = sort { $a->[7] <=> $b->[7] } @vals;

    # If more than half of the rates are greater than one...
    my $display_as_rate = @vals ? ($vals[$#vals>>1]->[7] > 1) : 0;

    my @rows;