8.13 Changing the way to write a difference (3.2.00)

8.13.1 Hermae Jaramillo

In a previous e-mail I expressed my concern about Maple changing the way it writes expressions in a "random?" fashion.

For example if inside a complicated expression I have h-d Maple could either write after some computations containg that binomial h-d, -d+h -(d-h) or -(-h+d).....I am not sure if I have seen the last one, but I suspect that is a valid one.

The problem is painful when I do substitutions. Those substitutions would be valid only for the session that I am running, since in the next session I would not know what Maple would give me.

Here is how I solved that problem.

>rho3 := eval(rho2, {signum(d-h)=-1, signum(h-d)=1, signum(-d+h)=1, 
        signum(-h+d)=-1});
 

where rho2 is a complicated expression having at least one of the four representations.

It seems to me that this is over killing.

Is there a more efficient way to handle this?. What is happening with Maple and its not consistent way to output expressions?.

8.13.2 Colin Birch (8.2.00)

The best solution seems to be to start with

> assume(h>d):
 

before you generate rho2. Then the problem never arises.