Re^6: floating point addition

But this remains strange to me:

perl -e 'print  201/10 == 20.10000000000000000 ? "eq" : "ne"'
eq

perl -Mbigrat -e 'print  201/10 == 20.10000000000000000 ? "eq" : "ne"'
eq

perl -e 'print  201/10 == 20.10000000000000142 ? "eq" : "ne"'
eq

perl  -Mbigrat -e 'print  201/10 == 20.10000000000000142 ? "eq" : "ne"
+'
ne
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The last two cases is where one can see the difference that bigrat makes, but should the comparison in the second case not yield false?

Comment on Re^6: floating point addition Download Code

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Re^7: floating point addition by choroba (Cardinal) on Jan 13, 2015 at 08:39 UTC
There's no 20.10000000000000142 under bigrat: $ perl -MO=Deparse -Mbigrat -le '$x = 201/10; $y = 20.1000000000000014 +2; print join " ", $x, $y, $x == $y ? "eq" : "ne"' BEGIN { $/ = "\n"; $\ = "\n"; } use bigrat; BEGIN { $^H{'float'} = q(CODE(0x6003db168)); $^H{'integer'} = q(CODE(0x600495668)); $^H{'binary'} = q(CODE(0x6004a8d28)); $^H{'bigrat'} = q(1); } $x = {_d => [10], _n => [201], sign => '+'}; $y = {_e => [17], _es => '-', _m => ['000000142', '010000000', '2'], s +ign => '+'}; print join(' ', $x, $y, $x == $y ? 'eq' : 'ne'); -e syntax OK [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]

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Re^7: floating point addition
by choroba (Cardinal) on Jan 13, 2015 at 08:39 UTC

$ perl -MO=Deparse -Mbigrat -le '$x = 201/10; $y = 20.1000000000000014
+2; print join " ", $x, $y, $x == $y ? "eq" : "ne"'
BEGIN { $/ = "\n"; $\ = "\n"; }
use bigrat;
BEGIN {
    $^H{'float'} = q(CODE(0x6003db168));
    $^H{'integer'} = q(CODE(0x600495668));
    $^H{'binary'} = q(CODE(0x6004a8d28));
    $^H{'bigrat'} = q(1);
}
$x = {_d => [10], _n => [201], sign => '+'};
$y = {_e => [17], _es => '-', _m => ['000000142', '010000000', '2'], s
+ign => '+'};
print join(' ', $x, $y, $x == $y ? 'eq' : 'ne');
-e syntax OK
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