January 5
Hi all,
I'm trying to understand the following reverse polish notation:
SSP xor DS xor or xor not
If I had the following:
SSP xor DS xor or not
then I know it would be:
NOT((S xor S xor P) or (D xor S))
What would SSP xor DS xor or xor not be?
Letsbefiends (talk) 01:44, 5 January 2015 (UTC)[reply]
- Ah, I got it! I wasn't pushing the value back onto the stack again. So it is:
- NOT(((D xor P) or (D xor S)) xor S)
- I had to reread that algorithm on the wiki a few times. - Letsbefiends (talk) 02:25, 5 January 2015 (UTC)[reply]
- Cool, I'll mark this Q resolved then. StuRat (talk) 03:16, 5 January 2015 (UTC)[reply]
- Well, RPN is to make it easy for the machine, not for people. :-) Bubba73 You talkin' to me? 04:24, 5 January 2015 (UTC)[reply]
- Presumably that first "D" in your answer was a typo, and you meant to state:
- not(((S xor P) or (D xor S)) xor S)
- -- ToE 06:04, 5 January 2015 (UTC)[reply]
![](https://upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/20px-Yes_check.svg.png)
Resolved
Here is how a human might resolve this, looking at the expression (and rewriting if necessary) by iterative replacing operators with their respective arguments:
- SSP xor DS xor or xor not
- S (S xor P) (D xor S) or xor not
- S ((S xor P) or (D xor S)) xor not
- (S xor ((S xor P) or (D xor S)) not
- not (S xor ((S xor P) or (D xor S))
CiaPan (talk) 05:52, 5 January 2015 (UTC)[reply]
- There's even a programming language based on this Forth (programming language) which used to be reasonably popular. It has often been described as a Write-only language ;-) Dmcq (talk) 16:32, 5 January 2015 (UTC)[reply]
Where is it? (Defining it analogically as the point where the sides subtend equal angles.) Double sharp (talk) 08:32, 5 January 2015 (UTC)[reply]
- The article on Fermat point would say something about it if there was anything so it's unlikely there is anything on Wikipedia. There;s a couple of papers on the web if you Google 'Fermat point sphere'. An opportunity to contribute to Wikipedia by adding to that article? Dmcq (talk) 16:43, 5 January 2015 (UTC)[reply]
- Hmm, this looks promising. Double sharp (talk) 21:45, 17 March 2016 (UTC)[reply]