# [r-t] Jump change notation

Robert Bennett rbennett at woosh.co.nz
Thu May 28 12:17:16 UTC 2015

```The routine described here looks ok.

On a practical level, how is this sort of ringing going to be taught?
If jump changes are in effect often during the lead, the traditional
ways of ropesight and hunting up and down will need to be modified.

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Wed, 27 May 2015 18:31:31 +0000
Subject:
Re: [r-t] Jump change notation

On Wed, May 27, 2015 at 2:12 PM Chris02

> It did occur to me that swapping adjacent bells could be considered

> as a jump change of distance 1. (As opposed to the more normal ones

> routine so it could handle not only the bell doing the jump, but

> also the ones shuffling up/down. It could then be used to handle

> swapping adjacent bells. (eg. Insert(3,4) to swap 3rds and 4ths

> place bell.) It could also be called to put in 1st place if needed

> and last place if needed. This would keep all the setting of the

> permutation array and all the error checking in one fairly simple

> routine.

Unless I've misunderstood you, I believe that this is exactly what I
am doing. That's what the k±1,k stuff is in the main loop:

| for k from 1 to N-2

|    if b[k] = null

|     if k-1 not in b

|       insert(k-1, k)

|     else

|       insert(k+1, k)

And similarly in the stuff that does the implicit leading and lying.

And, in fact, the test in insert() does do all the error checking (at
least all of it once you get past the preliminary, mundane stuff like
making sure everything is of the right type and length and so on).

And if you perversely choose to notate X (in major) as

(12)(21)(34)(43)(56)(65)(78)(87)

or

(12)(34)(56)(78)

or any of the many other such possibilities
it'll parse it just fine. And similarly, I am using the same code to
parse ordinary changes with places, which are just a degenerate case
of jump changes in Holroyd notation.

Or have I misunderstood your point?

--

Don Morrison <dfm at ringing.org [2]>

"It is the present, not the past, that dies."

-- Will Durant, _Fallen Leaves_