New RPL: New Commands

[Claudio L.]

(01-16-2017 04:39 PM)compsystems Wrote:  Hello Claudio

I use it for example in the input of a function.
"Enter algebraic expression in quotation marks" and then I transform into RPN, Since for many people entering an expression from a dialog box in RPN is not so simple. In RPN it is easier to do replacement and substitutions than in algebraic mode.

A command, even more important is the PART function, this always use it within my programs ..

The idea is that it is embedded within the language and not having to program it

Thread

PART function (TI89, HPPRIME) for HP48/49/50
http://www.hpmuseum.org/forum/thread-637...light=part

http://www.hpmuseum.org/forum/thread-650...light=part

Now we are talking: instead of asking for a command to implement the particular solution you chose, ask for a solution to the original problem. In this case, your problem are substitutions and replacements, not representing the expression as RPN (that's how you implemented a solution to the original problem, but not a problem by itself). There will be a rules engine (75% done but unfinished, so it's disabled for the time being) that will allow powerful substitutions using rules. You won't ever need to analyze the expression as RPN, just write the proper rules.

Regarding PARTS, it should be easy to implement, as it matches the internal representation of symbolics in newRPL.

Symbolics are stored as:
( Operator NumberOfArguments arg1 ... argN )

So getting the number of arguments, or extracting one of them is a trivial task.

On one hand, your use case of derivatives will be much better served by the rules engine (the rules engine is being written precisely to do derivatives and integrals based on tables of rules) so you won't really need PARTS, but being almost trivial to write I can include PARTS as a command in newRPL, might be useful for other things too.