Hi, I'm trying to figure out, how to differentiate the following expression:

I also don't get how to properly index (indefinite) sum terms... Grateful for any advice!

Can someone explain how to use Maple to get from Eq. (4) to Eq. (5) using Eq. (6) to (8)?

This is the Peng Robinson Equation of State (1976)

I tried some stuff like using algsubs  on Eq. (4) and then do some polynomial operations (expand, collect etc.) It did not work out though. I'm grateful for any advice!

Hi Guys, can someone explain how to resubstitute equations I already stated, into my final form (e.g. a derivative)?

I'm unable to substitute my g(x) expression (eq. (2)) into my derivative of f(x) (eq. (4). It only works if I state explicitly which variables to substitute via algsubs (last statement). However, for that I have to rename g(x)-->h(x). Can someone explain what I'm doing wrong here? I'd love to be able to tell maple just to use already given equations (that is g(x), eq. (2)) to simplify my derivative.

Thanks guys!

Hi guys,

I'm wondering whether it's possible to reverse my "substitution" in order to gain a nicer looking form:

In this example, I'd like to get the last "subs" statement without having to define a new variable "g_new" but instead, maple shall use the old name, and do the "resubstituion" automatically.

I hope someone can help. I'm also happy to get other advice, regarding my problem. Thanks!

Hi,

I'm not able to find a way to bring an equation into it's "polynomial" form:

I'd like this expression in the form of:

c1*v^3+c2*v^2+c1*v+c0 = 0

where c1...c4 are my coefficients

How can I do that?