ld

Etymology
Abbreviation of.

Symbol

 * 1)  binary logarithm; logarithm to the base 2
 * $$\log_{2}(x)=\mathrm{ld}(x) $$. $$ \mathrm{ld}(2) = 1 $$

Usage notes
The ISO 80000-2:2019 standard prescribes for the binary logarithm.