Equations in Annotations

Hello,

i have an assembly with tension springs. 

An dimensional annotation allows me to view the length of the spring dynamically while moving the asm.

So far so good.

It is possible to add custom text to the annotation field. What i am looking for now is, if i can add an equation in this filed that calculates the force, like (L0 - ) * R

I need this dynamically on assembly level. Is this possible?

Thanks a lot