Corresponding fix command & strain formula ?!?

Hi my friends!
Can I use :
fix 1 all deform 1 y erate 0.01 units box

and for computing strain use Almansi formula:
variable strain equal “0.5*((((ly)^2) - ((v_L0)^2))/((ly)^2))”

with Almansi formula strain will be obtained less than 0.01 in each step & does not correspond to fix command!
I have to use Almansi strain because I work on large deformation!


Fix deform has a “variable” option where you provide

two variables (defined by the variable command) for

the box length and rate as functions of time. Possibly

there is way for you to encode your Almansi formula

in that manner.