A case against the x<>y key

[Les Bell]

(05-11-2015 05:07 AM)Thomas Klemm Wrote:  

(05-11-2015 04:18 AM)Les Bell Wrote:  which it seems not everyone knows or agrees on

If unsure about the convention you can still use parentheses to make the expression unambiguous.

That's fine if the person writing the expression is unsure. Surely the bigger problem is the many readers who get it wrong? There have been times when I've been quite clear about what I mean, but I've parenthesized expressions to make it clear for the reader.

(05-11-2015 05:07 AM)Thomas Klemm Wrote:  

Quote:if variations between programming language are any indication.

I don't see how programming languages have anything to do with a mathematical expression like \(-9^{2^3}\). How would you even use that in a program?

What I am getting at is that a) designers of programming languages implement precedence and associativity differently, which is why programming language textbooks often contain definitive tables, and b) programming languages are often the route by which people internalize and develop the concepts of precedence and associativity. I believe similar variation exists in algebraic calculators, which may also colour people's experience and expectations. This isn't the first thread to touch upon this problem.

You seem to be adamant that algebraic notation is absolutely clear and unambiguous, and that any misinterpretation is down to stupidity on the part of the user. I agree that algebraic notation is - given a specified semantics common to both writer and reader - completely unambiguous, but I also tend to the view that people are only human and fallible, and miscommunication is possible because of the semantic variations that exist in this area. If that wasn't the case, this thread wouldn't exist.

What you're saying is, in effect, "If people would just do it right every time - like I do - then they wouldn't get it wrong". While this is true, it's not very helpful - they do get it wrong, and I'm more interested in exploring why. I'd rather help people than scold them.

My overall point is that, for many or most RPN users, the semantics of the problem domain governs their problem-solving keystrokes, and these problems never arise.