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", $energy_bin[$j];

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