# IRP=6  Fatt and Klikoff function

*IRP* = 6           Functions of Fatt and Klikoff (1959)

$${k\_{rl}}\quad  = \quad {\left( {{S^\*}} \right)^3}$$

$${k\_{rg}}\quad = \quad {\left( {1; - ;{S^\*}} \right)^3}$$

$${S^\*}\quad  = \quad \frac{{\left( {{S\_l}; - ;{S\_{lr}}} \right)}}{{\left( {1; - ;{S\_{lr}}} \right)}}$$

with Slr = *RP(1)*.

&#x20;Restriction: *RP(1)* < 1.