9:12 AM
Question related to 2014-P7 https://problems.tryapl.org/psets/2014.html?goto=P7_Revolutionary_Thinking
If the stationary circle is 5 and the rotating one 10, it needs two revolutions, is it? I'm asking because the test of my solutions tells me it is just one revolution. But with one revolution the circles are not in the same starting position.

@Richard Right, two revolutions, which is what the example shows too, right?

@Adám Yes for 10 {} 5, but for 5 {} 10 my solution alos gives 2, and the test field says it should be 1.
Result should have been 1 with (5) as left argument and (10) as right argument

A single rotation of the 10 will traverse the circumference of the 5 twice.

ah :) rotating the circle itself, not one rotation around the stationary circle :)

Yes.

9:22 AM
back to the drawing board, thanks!

6 hours later…
2:55 PM
If I want the names of the user defined functions and operators that make up a derived function, is taking the representation and parsing the first line of each item the most direct way to do it? In other words, something along the lines of:
`{1↓⍵↑⍨⍵⍳'←'}¨⊃¨⎕NR'f'`
Assume dfns and dops

Assuming they all have names.

3:12 PM
They will. Thanks.

@PaulMansour It may have a deeper nested structure.

You mean if one of the functions is itself derived?

Yeah.

OK, thanks.

@PaulMansour Like this:
```      Sum←{+⌿⍵}
Count←{≢⍵}
Div←{⍺÷⍵}
f←(Sum Div Count)Div Count
⎕NR'f'
┌─────────────────────────────────────────┬────────────┬─────────────┐
│┌────────────┬────────────┬─────────────┐│┌──────────┐│┌───────────┐│
││┌──────────┐│┌──────────┐│┌───────────┐│││ Div←{⍺÷⍵}│││ Count←{≢⍵}││
│││ Sum←{+⌿⍵}│││ Div←{⍺÷⍵}│││ Count←{≢⍵}│││└──────────┘│└───────────┘│
││└──────────┘│└──────────┘│└───────────┘││            │             │
│└────────────┴────────────┴─────────────┘│            │             │```

3:59 PM
Thanks!
Also, when analyzing ⍺⍺ and ⍵⍵, one needs to assign them to another name. Is that just a fundamental issue with ⍺⍺, etc, or could that be addressed?

4:15 PM
@PaulMansour I don't we'll address it, as the modern way is using `⎕ATX`:
```      Sum←{+⌿⍵}
Sum{⎕NR'⍺⍺' ⋄ ⍺⍺}⍬

Sum{61⎕ATX'⍺⍺' ⋄ ⍺⍺}⍬
┌──────────┐
│ Sum←{+⌿⍵}│
└──────────┘```

`⎕nr` on the other hand is the top hit
search for `source code of` doesn't give ATX sadly

I tend to wait a bit after release before changing things into using new functionality.

4:32 PM