CAS command question

[DrD]

(01-04-2017 12:56 PM)compsystems Wrote:  for DrD
If you enter the expression in quotation marks, the LEFT or RIGHT command works as it should ...

"Quotation marks" is ambiguous: there are single and double quotation marks. Each has it's object type, and means of handling. My example used string objects, (double quotes). However, as Arno K described, "left is left, and right is right."

left('x+y<4'); ==> x+y
left(CAS("x+y<4")); ==> 4

Referring back to my original post:

Un-intuitively, for a program, given a (perhaps random) list of expressions, those with a "<" inequality would need an exception handler. Requiring the list to be in a specific format is not user friendly. Real world expressions are unlikely to use single quotes, and further requiring them to be re-written in the specific inequality representation where the left side is always > than right side is just not practical.

Then there is the definition of the term "left" and "right," fundamentally. The similar command in Texas Instruments TI-Basic, as described here: http://tibasicdev.wikidot.com/68k:left seems better designed

Yes, Parisse explained the why of it, but as for "intuitively," I'm not so sure. What do you think?