flag: algebraic simplification

[shai lesh]

In the book Calculus on the HP 48G/GX by Coffin, a technique for logarithmic differentiation is given and a program FDER for is given which is called by another program doing the logarithmic differentiation. The FDER program is originally from Wickes's HP Insights II book. An example of FDER (formal derivative) in action is:

Level 2 stack: 5*x^2*a + 3*x*a^2
Level 1 stack: x

FDER (differentiation w.r.t. variable x) gives
'5 * (2 * x) * a + 3 * a^2'

as the result where "a" is another variable.

On my HP50G, I instead get

'10 * a * x + 3 * a^2'

(with textbook flag off).

I would like to get the answer as given by Coffin's book i.e. '5 * (2 * x) * a + 3 * a^2'. I have tried different flag settings but I could not have the first part '5 * (2 * x) * a' of Coffin's answer in place of the simplified form '10 * a * x' which I get. My HP50G is doing some "over-simplification" which I am not able to prevent.

Any help will be kindly appreciated.

Thank you.
Shailesh