just transform each prime p in the factorisation to a symbolic function g_p, then do standard differentiation and replace all derivatives with 1 and all undifferentiated g_p's with p
The derivative of a function is a cornerstone of mathematics, engineering, physics, biology, chemistry, and a large number of other sciences as well. Today we're going to be calculating something only tangentially related: the arithmetic derivative.
Definition
The arithmetic derivative a(n) or ...
As you can tell from this question and my previous one, I am determined to kill my SSD.
Let's write the shortest code to perform a simplified variant of the DoD 5220.22-M Wipe Method with only two writing passes.
Any programming language accepted, but the use of disk-wiping-oriented libraries i...
This is essentially the same thing as this question, except harder. You are again to write a program that gets from the lower-left corner of a rectangle to the upper-right corner. However, this time diagonal moves are allowed.
The program will accept an ordered pair (width, height), and use thes...
GolfScript gets its own way far too often and I feel that a repository of handy hints for golfing in J might help in the fight against the evil empire. What tips do you have for making this already terse language shorter?
For those wanting to learn J, the obvious place to begin is the jsoftware ...
hmmm, it never occurred to me before that 6! = 8*9*10. Are there other factorials that can be expressed as the product of consecutive integers except the factorial itself?
I was playing around with hypergeometric probabilities when I wound myself calculating the binomial coefficient $\binom{10}{3}$. I used the definition, and calculating in my head, I simplified to this expression before actually calculating anything
$$
\frac {8\cdot9\cdot10}{2\cdot3} = 120
$$
An...
J, 30 chars
0:`([*[:+/[:%[:q:[:%:[:*:])@.*
Try it online!
Sample input:
0:`([*[:+/[:%[:q:[:%:[:*:])@.* _8
_12
0:`([*[:+/[:%[:q:[:%:[:*:])@.* 0
0
0:`([*[:+/[:%[:q:[:%:[:*:])@.* 8
12
How it works:
0:`([*[:+/[:%[:q:[:%:[:*:])@.* N
XX`YYYYYYYYYYYYYYYYYYYYYYYY@.Z if Z then Y else X end
0: ...
When the program you write for a challenge writes/outputs to multiple of the default outputs, are you, the answerer allowed to state which one is counted for the purposes for the challenge?
For example, if my program
Leaves the output on the stack
Outputs to STDOUT
Am I allowed to say that t...
Rank means to which dimension the verb is applied. For example, for a 2D array, +/ reduces across columns (rank 0), but +/"1 reduces across rows (rank 1).
Currying makes a monadic verb from a dyadic one. (3&+) 5 gives 8.
According to our meta consensus (which isn't really enforced), that l would count as two bytes. Couldn't you just use the first byte of the source code?
@PhiNotPi your hexaglyphs look even more fun if you compute them as usual, but then swap the roles of sides and corners of the hexagon (i.e. swap the radii of the points):
@quartata According to meta consensus (which, again, isn't really enforced), perl -pe code is one byte more than perl -e code, but perl -p file is three bytes more than perl file. It's the edit distance in both cases.
@MartinBüttner There's also a bunch of other variations that can be done, like using more points but then placing restrictions on which points can connect to which.
I want to implement a geometry-based version as well, but it seems that splitting a line around intersections isn't easily doable in Mathematica, so it probably won't be very golfy
if I do, it should be trivial to use any number of points though
The general process is 1) take a set of points and a restriction (if desired). 2) draw the lines between all points, obeying whatever restriction. 3) remove all lines that would have been drawn no matter what.
Okay, I propose a shortest-key-logger challenge. As explained by the gentleman at "Are key-logger questions allowed?", strict rules have to be imposed in order to make this challenge valid for PPCG.
The key-logger has to run on Windows or on Linux (any programming language is welcome).
Upon exe...
Here's our to-do list for the project:
Close all existing code-trolling questions (or maybe re-tag those three I mentioned).
status-declined - if locked or deleted, closing might not matter, so we may or may not close them all first
Lock all the more popular ones (>20 answers or >20 upvotes, ...
Inspired by this question about packing into this format.
Occasionally I see a completed crossword and being as I am, I can't be bothered to find out what the solutions to the clues actually were.
Input:
A 2D string (any format, newline separated, 2d list etc.)
Blank squares will be represent...
@ChrisJester-Young Well then, I'll look at it sometime soon. I'm still going through Learn You a Haskell as my intro to functional programming. Or can you recommend another tutorial?
I feel like underhanded is probably a category that could be revived if someone comes up with an exceptionally good challenge. Most of the time, though, it gets reduced to gimmicks that everyone's already seen multiple times.
@ChrisJester-Young Well, How to Design Programs is available online like Learn You a Haskell. Not so with Realm of Racket. I'll stick with HtDP, for now
The derivative of a function is a cornerstone of mathematics, engineering, physics, biology, chemistry, and a large number of other sciences as well. Today we're going to be calculating something only tangentially related: the arithmetic derivative.
Definition
The arithmetic derivative a(n) or ...
As you can tell from this question and my previous one, I am determined to kill my SSD.
Let's write the shortest code to perform a simplified variant of the DoD 5220.22-M Wipe Method with only two writing passes.
Any programming language accepted, but the use of disk-wiping-oriented libraries i...
The formula $$(n!-1)!=\frac{(n!)!}{n!}=\prod_{k=n+1}^{n!} k$$ gives an infinite family of examples.
I was playing around with hypergeometric probabilities when I wound myself calculating the binomial coefficient $\binom{10}{3}$. I used the definition, and calculating in my head, I simplified to this expression before actually calculating anything
$$
\frac {8\cdot9\cdot10}{2\cdot3} = 120
$$
An...
When the program you write for a challenge writes/outputs to multiple of the default outputs, are you, the answerer allowed to state which one is counted for the purposes for the challenge?
For example, if my program
Leaves the output on the stack
Outputs to STDOUT
Am I allowed to say that t...
Here's our to-do list for the project:
Close all existing code-trolling questions (or maybe re-tag those three I mentioned).
status-declined - if locked or deleted, closing might not matter, so we may or may not close them all first
Lock all the more popular ones (>20 answers or >20 upvotes, ...
