# V1.0, 14th Feb 2017: Focus_Derived_Posn - NICS0R00
# Computed Focus Position (from RTHK report) as a function of focus temperature NIC0TR30
#
# V1.1, 30th Aug 2019: Now modified to return just the measured focus position
#
# ----------------------
#
# Focus_Derived_Posn
#
VAR_tf := NIC0TR30  - 20.0;
VAR_fac := 0.0;
VAR_idx := 1.5;
if (VAR_tf >= 0) then
    return (NIC0PR15 + VAR_fac * (VAR_tf)**VAR_idx) ;
else
    return (NIC0PR15 - VAR_fac * (-1.0*VAR_tf)**VAR_idx) ;
endif;