CAS command question

[DrD]

Parisse,

1.

Quote:I have explained how you can program the same functionnality whatever the order is. In fact it's even better because the resulting program is more general.

We seem to find agreement here: It takes an EXTERNAL program like you describe, because the CAS left() and CAS right() commands are INCOMPATIBLE with other CAS commands that use an EXPRESSION as an argument, due to the INCONSISTENT CAS evaluated result, in order to provide a more "general functionality".

2.

Quote:I don't understand why it's so important for you to keep the ordering

The reason why it is important is that other ppl commands require an expression as an argument. The CAS left() and right() commands are available to separate the expressions, but they, inconsistently, return their namesake. Han, and I have suggested that new commands: lhs() and rhs(), could be designed to return the left and right side expressions, to avoid the need for extra programing requirements to overcome this shortcoming.

3.

Quote:the CAS logic: you need to eval the expression

This argument is illogical, for this kind of CAS command. The [Help] topic omits inequalities, yet the commands still process them, just poorly. Arno K has explained in pure logic that left is left, and right is right. There is a certain beauty in that statement, and I totally get what he is saying there.

4.

Quote:The parser steps returns the expression as is (unevaluated)

Use the force: This return content could be used for new lhs() and rhs() commands, to keep something like x<4, from becoming 4>x, and lhs(x<4); would become x, and rhs(x<4); would become 4. Students wouldn't need EXTERNAL programs, (or techniques), to overcome the dyslexic CAS left() and right() expressions. Only then would other hppl commands be able to work, homogeneously, with them.

5.

Quote:DrD, I think you are still confused

Agreed. I mentioned earlier that we probably agree on many more things than this post seems to suggest ...

I'm going to suggest again that this is a bug. I'll respect that you don't understand, and that you probably won't, or can't change; or won't, or can't implement, the suggested new commands. Use of left() and right() commands may cause other CAS commands, (requiring an expression), and programs containing them, to fail. How would YOU define the term, "bug?"