Hello!

I am working with very complicated PDE's, and I am stuck with the chain rule.

The variable k is dependent on T.

T is dependent on x and y.

The expression for k is quite complicated, and will change depending on the application.

So, we are trying to not include the expression for k in Maple, but only that k=k(T), and carry this information throught the calculations.  I do need to calculate the derivative and carry this information as well.

Hello!!!

I have an equation written in several terms: Q:= T1+T2+...+T37.

I want Maple to present my equation Q in the order I typed but it sorts it in an strange way, for example, the order would be: Q:=T5+T3+T35+...+T3.

Because terms T1...T37 are quite complicated expressions, I need Maple to keep them in the order I indicated in the sum.

Is there anyway that I can force Maple to keep it in the right order?

Thanks!

# Hello!
# I've been trying to replace one expression into another, which includes the derivative of a quotient, but algsubs doesn't work and I don't know why.
# To make it simple, I want to replace a expression from rho into the expression for q_x. Let's say rho is a function of alpha.
>
> restart;
> alias(rho = rho(x, y, t)); alias(rho_an = rho_an(x, y, t));
> alias(p = p(x, y, t));
> alias(q_x = q_x(x, y, t));
> alias(alpha = alpha(x, y, t));
>
>
> rho_an := alpha;