use strict;
use warnings;
use Config;
use Data::Float;

# Set $prec to the required value
# for "%.*e" formatting for the
# nvtype that we have.

my $prec = 35;  # __float128

# Amend $prec's value as needed
if( $Config{nvsize} == 8 ) { $prec = 16 }
elsif( $Config{nvtype} eq 'long double' ) {
  $prec = 20
     unless( $Config{longdblkind} == 1 ||
             $Config{longdblkind} == 2 );
}

my $val  = 1.0;
my $down = Data::Float::nextdown( $val );
my $up   = Data::Float::nextup  ( $val );

printf "%.${prec}e %a\n", $down, $down;
printf "%.${prec}e %a\n", $val,  $val;
printf "%.${prec}e %a\n", $up,   $up;

##</code><code>##

9.9999999999999989e-01 0x1.fffffffffffffp-1
1.0000000000000000e+00 0x1p+0
1.0000000000000002e+00 0x1.0000000000001p+0