my %test =      (
'0.0000000075,9'                        => '0.000000008',
'-0.0000000075,9'                       => '-0.000000008',
                        );

my $space = '.' x 25;
foreach my $test (sort {(split /,/,$a)[0] <=> (split /,/,$b)[0] } keys %test) {
        my ($wert,$stellen) = split /,/,$test;
        my $gerundet = &{$sub} ($wert,$stellen);
        print "\'$wert\'" . substr ($space,0,25 - length ($wert)) . "auf $stellen Stelle(n): \'$gerundet\'" . substr ($space,0,25 - length ($gerundet)) . ($gerundet eq $test{$test} ? ' OK' : " FEHLER! Erwartet \'$test{$test}\'") . "\n";
}