Curve fitting units

1) To be able to calculate "sigma -23" obviously both must be of same dimension. Itz can't work if sigma has unit ksi and 23 is unitless

2) The arguments of functions like exp, log, sin, etc. must be unitless. Thats not a limitation of Mathcad, though 😉

3) If this is an old empiric formula, you may assign unit ksi to sigma and then use log(sigma/ksi-23) to make it work. No need to create a unitless variable manually.

4) Concerning cycles you may define your own "unit" (its not a unit anyway) for this. Assign cycles:=1 and label the word cycles as "unit".