which is the same as the Stormer's formula with For and we obtain the frequently used formula
(7.47)
The Cowell formulas are implicit for i. e. the unknown value occurs not only on the left but also, as an argument in on the right. The resulting equation for which is non-linear except when the differential equation is linear, can be solved by iteration. As a predictor formula, Stormer formula (7.38) is recommended, because it uses the same combination of values of on the left.
For 
and 
we obtain the frequently used formula 
i. e. the unknown value 
occurs not only on the left but also, as an argument in 
on the right. The resulting equation for 
which is non-linear except when the differential equation is linear, can be solved by iteration. As a predictor formula, Stormer formula (7.38) is recommended, because it uses the same combination of values of 
on the left. 
