The ' ** ' operator does not work on negative numbers as an expected way .

[unique1984]

PHP Version : PHP 7.3.3-1+020190307202245.32+stretch1.gbp32ebb2
(Php versions 7.1 and 7.2 I tested it, and behavior is the same.)

Symfony Version : 4.2
Twig Version : symfony/twig-bundle": "4.2.3
Lsb Release : Debian GNU/Linux 9.8 (stretch)

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in raw php code (as expected):
-2 ** 2 = 4

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in twig (something is wrong in here);
{{ -2 ** 2 }}
{{ -2 ** 3 }}
...

[stof]

I think this might be related to some precedence issue in the way this is parsed. It may be parsed as - (2 ** 2) here instead of (-2) ** 2 (and so using a variable to store the -2 or using braces may not be affected)

[stof]

btw, in PHP, if you remove the usage of a variable but inline the number (making it equivalent to the Twig code), you get the same behavior than the one you report in Twig.

[unique1984]

I get it, in parenthesis it didn't work but defining a negative number variable works.
Thank you @stof , have a nice day.

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This way works!

[stof]

yeah, parenthesis may not work, because Twig would parse it as expected, but compile it to PHP without braces, and so be affected at the PHP level.