- my $unit = int(log($_[0]) / log(1000) - ($_[0] < 1));
- my $float = $_[0] !~ /^ (?: 0*\.)? [0-9]{1,3} $/x;
- sprintf('%*.*f%*s',
- $float ? 5 : 3, $float, # length and tenths
- $_[0] / 1000 ** $unit, # number
- $float ? 0 : 3, # unit size
- $#{$opt{units}} >> 1 < abs $unit ? "e$unit" : $opt{units}->[$unit]
+ my $unit = int(log(abs $_[0] || 1) / log(10) - 3*($_[0] < 1) + 1e-15);
+ my $float = $_[0] !~ /^0*[-0-9]{1,3}$/;
+ sprintf('%3.*f%1s',
+ $float && ($unit % 3) == ($unit < 0), # tenths
+ $_[0] / 1000 ** int($unit/3), # number
+ $#{$opt{units}} * 1.5 < abs $unit ? "e$unit" : $opt{units}->[$unit/3]