Talk:Triangular array

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Was that a good idea?

@David Eppstein: Er, your edit changed a definition that I thought was helpful precisely because it was more formal than the previous informal one to basically a repetition of the previous sentence. I wanted to use formal mathematical notation like $a ij$ . (The exact wording I chose has the benefit of being correct whether you're using 1-based or 0-based indexing.)

I'd rather include something more formal like I originally wrote, or just delete the redundant sentence. Since either would do violence to your edit, could we discuss it?

(I was also thinking of describing the standard implementation in computer memory per https://stackoverflow.com/questions/17406593/triangular-array but the inverse mapping is a bit tricky. I.e. given $k = i (i +1)/2 + j$ , how do I re-derive $i$ ? It's something messy involving the integer square root.)

38.39.199.2 (talk) 05:03, 30 October 2019 (UTC)[reply]

Especially in the lead, but more generally in all Wikipedia articles, formality needs to take a back seat to understandability. It does not make it any more accurate, rigorous, or correct to express the same thing in notation rather than words; it merely makes it harder for the uninitiated to understand. We should be working to make mathematics understandable to all, not building ivory towers of obscurantism to keep others out. See WP:TECHNICAL.

As for your re-derivation of i, that one is messy enough that a formula rather than words probably is the right way to express it. It's

i=\left\lfloor {\sqrt {2(k+1)}}-{\frac {1}{2}}\right\rfloor .

But you should probably find a reliable source for an equivalent formula before adding it to the article rather than taking my word for it. —David Eppstein (talk) 05:30, 30 October 2019 (UTC)[reply]