printf PLOUT "%.5f %.5e %.5f\n", $energy_bin[$i], $spec_cps[$i][$j], $sigma_cps[$i][$j];

##</code><code>##

use strict;
use warnings;

my @energy_bin = (1, 2, 3);
my @spec_cps = ([5, 6], [7, 8], [9, 10]);
my @sigma_cps = ([15, 16], [17, 18], [19, 110]);

for my $j (0 .. $#energy_bin) {
   printf "%.5f %.5e %.5f %.5e %.5f\n",
     $energy_bin[$j],
     $spec_cps[$j][0], $sigma_cps[$j][0],
     $spec_cps[$j][1], $sigma_cps[$j][1];
}

##</code><code>##

1.00000 5.00000e+000 15.00000 6.00000e+000 16.00000
2.00000 7.00000e+000 17.00000 8.00000e+000 18.00000
3.00000 9.00000e+000 19.00000 1.00000e+001 110.00000