Contemplating the use of J at elementary mathematical level, I was curious
as to what the accepted approach for the sigma notation might be...
After all, this is even present on calculators these days, and students
expect something like it to be available.
A site search - surprisingly - does not yield much.
This is what I came up with so far, obviously much polish and embellishment
needed.
First off, I have a dyadic helper verb called 'irange', that gives an
integer range. Saves me some convolutions when using i.
If I have understood the J philosophy so far, sigma will need be an adverb,
modifying the verb which will represent the function itself. Personally, I
am not quite happy with this, as it breaks with conventional notation, but
what the hell. (I would prefer something that would more closely resemble
the algebraic form sigma(function, from, to) but that would mean sigma
needs to be a verb, and then things get messy... unless someone has a
better idea.)
So I ended up with
sigma=: 1 : '+/ u (0{y) irange 1{y'
used thus:
*: sigma 1 3
14
I think it might be a bit of a hard sell.
Comments, suggestions, reprimands...?
I'd also be curious as to the established approach for summation of
infinite series. Would that utilise something based on (^:_) ?
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