And to protect you from it, you can use the following lucky clover charm (polar plot r=cos(2theta) ): https://www.wolframalpha.com/input?i=+plot+r%3Dcos%282theta%... whose perimeter can also define a constant 4*E(-3) ~ 4 * 2.4221

https://www.wolframalpha.com/input?i=plot+r%3Dcos%282theta%2...