You could start with Perl's built-in rand function. Type the following at command-line to get the documentation on rand:

perldoc -f rand
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What sort of data structure are you thinking about? I would probably store the elements in a hash table with gate ID as lookup key:

my %gates = (
  'gate001' => {
    'gate_type' => 'FLIPFLOP',
    'inputs' => [],  # array of input values
    'outputs' => [], # array of output values
  },
  'gate002' => {
    'gate_type' => 'XOR',
    'inputs' => [],  # array of input values
    'outputs' => [], # array of output values
  }
);
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If I want to insert 20 random input values between (-1.0, 1.0) to gate001:

for (1..20) {
  push @{$gates{'gate001'}{'inputs'}}, rand(2.0) - 1.0;
}
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