newRPL: symbolic numbers

[Nigel (UK)]

(12-23-2014 09:01 PM)Claudio L. Wrote:  

(12-23-2014 05:57 PM)Nigel (UK) Wrote:  It is quicker to type 2*(3+4) than '2'*('3'+'4').

Typing is the only problem I see with using quotes. In your example, it's much more comfortable to type the dot.
You'd have to press the quote, type the number, then cursor right to get out of the quote.
Makes writing expressions a pain.

Or, accept that every number you type inside quotes will become exact, dot or no dot.
Would that be a nuisance?

A last resort could be to use a trailing dot as the approx. indicator inside symbolics:
2 is a number --> approx.
'2' is symbolic --> exact
'2.5' is symbolic, dot is there but is not trailing --> exact
'2.5.' is an approx. number

The trailing dot is a reasonable idea. However, is it necessary? I'm not sure why anyone would want a number like 2.5 to be treated as an exact number. Perhaps this is because I'm a physics teacher - I insist that all calculated results are given to an appropriate number of significant figures, usually no more than three. Anyone who writes 5/2 ohms for the resistance of a resistor would lose a mark, because they are claiming to know the resistance to an infinite number of significant figures and that can never happen.

So I would suggest:

2 or 2. is a number --> approx.
'2' is symbolic --> exact
'2.5' is symbolic --> approx because of the dot
'2.5.' is symbolic ... --> exact! Exact numbers with decimals might be needed sometimes, but for me at least they would be a rare occurrence and so they should be the harder of the two to type.

I'm not entirely happy with this either. I shall continue to think!

Nigel (UK)