If you need a particular format of your number in order to get a desired behavior, you need to control how your number gets converted into a string. This is usually done using sprintf. For example 
$ifac{sprintf "%.3f" $factor}

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will cause the key accessed to be a floating point number with 3 decimal places, thus forcing the numbers to yield appropriate strings. It also avoids the potential 6.269999999999999999 problem.

In your case, your issue begins with your hash creation: 

use Data::Dumper;
my %ifac= (
14.152 => "JCI",
9.334 => "JHEP",
5.745 => "JIMM",
6.270 => "JID",
1.480 => "JRN",
6.105 => "KI"
);
print Dumper \%ifac;

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prints 
$VAR1 = {
          '6.105' => 'KI',
          '1.48' => 'JRN',
          '9.334' => 'JHEP',
          '5.745' => 'JIMM',
          '6.27' => 'JID',
          '14.152' => 'JCI'
        };

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You need to control string format on input, which means using strings not numbers for initialization: 
my %ifac= (
'14.152' => "JCI",
 '9.334' => "JHEP",
 '5.745' => "JIMM",
 '6.270' => "JID",
 '1.480' => "JRN",
 '6.105' => "KI"
);

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#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re: decimal numbers as hash keys by kennethk
in thread decimal numbers as hash keys by Alex31

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