Posts: 2,448

Threads: 90

Joined: Jul 2005

Hi Martin

I would add "editability of equations" to the must have part. If it had that, then the machine would be capable of functioning like the "formula entry" machines out there--giving it a tri-functionality: RPN, old-time ALG-postfix, and Formula. To put the "answer int oa chain of formulas, I suppose you would merely send the evaluation into a variable, and use the variable in the next chain---but an "ans" button could be used, too (like, who needs the cube root feature-replace it!).

I would also change the equation writing system to eliminate the existence of the "unary minus." I find that to be an annoying business--different from machine to machine. (Much worse on the 32sii BTW because it is evaluated before y^x in most but not all circumstances!). The 17bii has no unary minus, and evaluates each minus sign to "reverse" the sign one by one, in other words, you can have 4*---7 in the equation list, and it will evaluate to -28. If you do the same on a 48GX, in 'algebraic' it will parse it to '4*-7' when it is entered to the stack. b If you try '4-*7' it will catch the error during the parsing, and tell you to fix it. These sorts of behaviors make more sense to me.

Regards,

Bill