[Closed] if/then/else_jumps

Hi guys,i got a little problem during scripting my muscles,
i have a point at the start of my muscle,i want it to move along X_axis about to 10 units,but when i make a script for that it jumps,in fact it dosen’t have a flow motion for 10 units,i dono is there a function or sth else to make it flower than this jumping moving???
clearly i’m looking for a flower mothion than a snaping motion.

the script i used is here :raely simple:

z_angle  = "the value of z between twe bones"

if z_angle > 0 then 
abs(z_angle)*1.2
else0

this is clear but i dont know why it jumps insted of haveing a flow motion :shrug:

i was wondering if you scripter help me,i realy need to know how to solve it.