[{echo php:sqrt(-1)}]
[]
{echo php:sqrt(-1) ?? 'not a number'}
not a number
{echo php:intdiv(7, 2)} {echo 7 % 2}
3 1
{echo 7.5 % 2} {echo php:fmod(7.5, 2)}
1 1.5
{echo 0.1 + 0.2}
0.3