The Nineteenth Byte - 2015-11-18 (page 1 of 9)

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12:08 AM

0

Q: shortest code to copy a file with incremented pattern

let’s say I havesomefile runningsomescript somefile dir 2 (where 2 represent the pattern length) would copysomefiletodirso thatdirwould copies ofsomefilewith the following pattern : 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 0g 0h 0i 0j 0k 0l 0m 0n 0o 0p 0q 0r 0s 0t 0u 0v 0w 0x 0y 0z 0A 0B ...

@TanMath Sorry, I was in my car. I haven't quite figured out your code yet. I'll take another look a bit later.

@Dennis Do you CJam while driving? I've heard that's the leading cause of traffic collisions among code golfers.

guys

I have a new profile picture

user image

@AlexA. No, I just got home. :P

El'endia Starman

@orlp It's the diagvote!

12:22 AM

Seriously, kids, don't CJam and drive!

El'endia Starman

(Used by the dianoga.)

@Dennis The C doesn't stand for "car"? :P

Cherry AFAIK.

(I know, I was kidding)

It should be "cram." CramJam.

On one occasion, I pulled over to post an answer though. It was a CnR, and the deadline would have had passed if I had waited until I got home.

12:24 AM

user image

El'endia Starman

@Dennis Now that's dedication.

4

I didn't mind the robbing points, but the cop answer was shorter than my shortest one...

Hasty first revision posted from the side of the road:

codegolf.stackexchange.com/revisions/54730/1

later...

> added 2506 characters in body

2

@El'endiaStarman I would have called it obsession, but I like your wording better.

@orlp Ah yes, the fabled no-vote.

12:29 AM

Sep 17 at 1:15, by Doorknob

user image

did you know that my reputation is OVER 9000?!

Cᴏɴᴏʀ O'Bʀɪᴇɴ

NOICE

@Doorknob Downcarrot?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

Mine's over 1337 :P

I now officially have 1 rep point on codegolf for every 5 I have on stackoverflow

12:30 AM

mine are almost equal

Cᴏɴᴏʀ O'Bʀɪᴇɴ

I feel like I should write a sort of lore to PPCG :P\

by the way

I'm done now

El'endia Starman

I have almost no rep on Stack Overflow. :P (After taking the 100-point rep bonus for passing 200 rep on any site into consideration.)

I optimized the constants

inline double fast_sin(double x) {
    // Polynomial constants generated with sollya.
    // fpminimax(sin(x), [|1,3,5,7|], [|D...|], [-pi/2;pi/2]);
    // Both relative and absolute error is 9.39e-7.
    const double magicround =  6755399441055744.0;
    const double pi         =  3.14159265358979323846264338327950288;
    const double invpi      =  0.31830988618379067153776752674502872;
    const double a          = -0.00018488140186756154724131984146140;
    const double b          =  0.00831189979755905285208061883395203;

My PPCG, meta.SE, and SO rep are all within a range of 2000

12:32 AM

maximum error is now 9.39e-7 (funnily enough both absolute and relative), in ~5 cycles

El'endia Starman

nice

oh, spotted an optimization

haha

guess I'm not done

El'endia Starman

....nice...r.

uint64_t period = u.i & 1;

period << 63

notice something useless about this?

the & 1? :P

12:34 AM

exactly

@orlp My PPCG / my SO rep is very close to (within 0.007 of) pi + gamma/2.

... what

Yeah

Calvin's Hobbies

What number is gamma?

0.5772156649015...

Euler–Mascheroni constant

The Euler–Mascheroni constant (also called Euler's constant) is a mathematical constant recurring in analysis and number theory, usually denoted by the lowercase Greek letter gamma (). It is defined as the limiting difference between the harmonic series and the natural logarithm: Here, represents the floor function. The numerical value of the Euler–Mascheroni constant, to 50 decimal places, is 0.57721566490153286060651209008240243104215933593992…. == HistoryEdit == The constant first appeared in a 1734 paper by the Swiss mathematician Leonhard Euler, titled De Progressionibus harmonicis...

@Doorknob abs((12570 / 3671) - (π + γ/2)) --> 0.0060

12:40 AM

interesting

my PPCG rep / my Puzzling rep is close to 11 + 1/(4pi)

apparently

:O

@orlp The & 0xffffffff is also redundant, as far as I can tell.

@orlp u r gud c++

and my Puzzling user ID / my PPCG user ID is close to pi to the -4

Whaaaaat

Math everywhere

Math Overflow

12:43 AM

...

Calvin's Hobbies

2^2 <= 3

Oh no, I mathed everywhere.

ew

@Calvin'sHobbies In Z/2Z, 2^2 = 2*2 = 0 and 3 = 1, so indeed 2^2 <= 3.

El'endia Starman

:3

12:46 AM

> In Z/2Z

O_o

P ≈ NP

But then <= has no meaning.

@Doorknob The integers modulo 2

oh

that makes more sense

Calvin's Hobbies

pi mod e = pi mode

12:48 AM

Pie a la mode

only in pitalics

El'endia Starman

Edna Mode

......and guest.

@feersum it is not

u.i & 0xffffffff takes the least significant 32 bits of the 64-bit value u.i

so I was trying to find something interesting about the inverse of my PPCG user id...

user image

THANKS WolframAlpha...

u.i & 0xffffffffffffffffull would be redundant

El'endia Starman

12:51 AM

@Doorknob hahaha...

@orlp But you immediately truncate it to 32 bits.

Calvin's Hobbies

strawpoll.me/6034486

If they were both signed it would matter, but I think it doesn't if either is unsigned.

@Calvin'sHobbies totally 7

El'endia Starman

@Calvin'sHobbies WHY CAN'T I PICK ALL?!?

Calvin's Hobbies

12:53 AM

@El'endiaStarman that's irrational

@Doorknob Not to be a spoilsport, but that should work for my PPCG ID as well.

Better actually, since it's higher.

Actually it doesn't matter even if they're both signed.

@Calvin'sHobbies one vote for everything except phi. Sorry @PhiNotPi :P

now pi's winning which is wrong because 7 is the best irrational

test

@Doorknob I think I was the only vote for e.

12:54 AM

@feersum it wouldn't matter if both were unsigned

not sure how sign extension works when one is unsigned and the other is signed...

just to be safe I truncate, but I guess it could be redundant

(because the sign extension is crucial in this case)

fun fact!

tan(x)*tan(x+pi/2) = -1

New Sandboxed Posts

0

A: Sandbox for Proposed Challenges

Pythagoras' Other Leg code-golf Pythagoras had his leg blown up in the war. It had to be amputated, and though he nearly died, he pulled through and made a full recovery. Now, after a year of walking with crutches, he gets the privilege of getting a prosthetic leg! Thing is, though, there are s...

lol, "to be safe"

flaming undefined behaviors everywhere but let's be safe now :P

El'endia Starman

 sin(x)cos(x)
-------------
-cos(x)sin(x)

well, AFAIK this code is perfectly well behaved under IEEE754 and two's complement

I'm not saying it won't work.

What are you using this for?

12:59 AM

you're right though, it seems that it is redundant

still not removing though :P

@feersum fun

I enjoy writing fast code

Applied fun or theoretical fun?

right now I'm not using this

so I guess theoretical

but the function itself could be practically useful

El'endia Starman

> theoreticla

Just because @AlexA. probably missed it.

@El'endiaStarman you saw nothing

El'endia Starman

[whistles]

1:00 AM

@El'endiaStarman I appreciate you saving this moment in time for me :)

El'endia Starman

:)

Hedgehogs love birds.

They're tasty.

uh

@feersum this is an old project of mine though

only recently I laid my eyes on sollya, which allowed me to compute the minimax polynomial

so I finished it

(before I used a hand-generated polynomial based on the following set of equations)

f(x) = ax^5 + bx^3 + c
f(pi/2) = 1
f'(pi/2) = 0
f(pi/6) = 1/2

Calvin's Hobbies

Favorite trig functions?

user image

1:03 AM

@Calvin'sHobbies trafficsine?

El'endia Starman

> trafficsine

@Calvin'sHobbies wat votes for all of them

El'endia Starman

lol

> leasecosine

lolz

Cosign a lease

sin wins though

it's the primitive

although, what about cos

1:04 AM

Trigonometry class should really be called sin city.

can a good argument be made which is more primitive of sin and cos?

yes

El'endia Starman

@orlp sin(0) = 0 and sin(x) ~= x when x is small.

@MitchSchwartz Hi there, I just sent an email to shinh to have the deadlines synchronised. I have to admit, it didn't occur to me that the problems could be solved with a similar strategy until I noticed your 116 char submission. Great job by the way! I eagerly wait to study your submissions :)

@El'endiaStarman buuut cos(x) = cos(-x)

El'endia Starman

1:06 AM

@Doorknob sin(-x) = -sin(x)

Also cool...

OH. AND...d/dx sin(x) = cos(x).

Calvin's Hobbies

can a good argument be made which is more primitive of sin and -sin?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

sin(x) = sin(x)

cos has a better formula in terms of e^x.

El'endia Starman

@Calvin'sHobbies sin^2 is positive, so pick the one with the same sign.

"Cos" is terrible, lazy textual slang for "because."

1:08 AM

can a good argument be made which is more primitive of sin(x) and cos(x-pi/2)?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

My favorite identity though is log(xy) = log(x) + log(y)

El'endia Starman

Logalogalogalooooog!

I prefer ln(a^x) = x ln(a)

@CᴏɴᴏʀO'Bʀɪᴇɴ e^(pi*i) = -1

Hello all!

1:09 AM

@CᴏɴᴏʀO'Bʀɪᴇɴ log(1) = log(-1) + log(-1)

:D

log_a(x) / log_a(b) = log_b(x)

El'endia Starman

@orlp ಠ_ಠ

@Doorknob That is actually false did u no

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@Doorknob That one is good to othough

El'endia Starman

That is cool though. :P

Calvin's Hobbies

1:10 AM

@El'endiaStarman communist shrew ;)

@AlexA. are you sure?

@orlp #mathtrollin

@Doorknob ya

my calculator says it's right :P

(I'm in the middle of doing math homework actually so I have it right here)

El'endia Starman

@Calvin'sHobbies I'm sure he's wise though, so he probably has a reason... :P

ur calculater isnt rite

1:10 AM

@AlexA. AFAIK it's true

why is it false?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

e^(pi*i) = -1.00000000001

@orlp I'm #mathtrollin

El'endia Starman

I've used that log base conversion before. It's definitely true.

Hello? What is going on?

Of course that shit is true

El'endia Starman

1:11 AM

@CᴏɴᴏʀO'Bʀɪᴇɴ GASP

@CᴏɴᴏʀO'Bʀɪᴇɴ e to the pi minus pi :P

Also, I hear the 4th root of (9^2 + 19^2/22) is pi.

2

Calvin's Hobbies

http://strawpoll.me/6034592

El'endia Starman

IIRC, e^(pi*sqrt(163)) gets really close to being a whole number.

@Calvin'sHobbies ಠ_ಠ

@Calvin'sHobbies no you didn't just do that

1:12 AM

@Calvin'sHobbies seriously?

El'endia Starman

@Calvin'sHobbies ಠ_ಠ + angry

suspends Calvin for rick rolling

2

Anonymous

@Calvin'sHobbies You adsjflkdshfkjsndfjsbguidfjgn

Calvin's Hobbies

I couldn't help it :p

@El'endiaStarman that would be (╯ಠ_ಠ）╯︵ ┻━┻

Cᴏɴᴏʀ O'Bʀɪᴇɴ

1:13 AM

@El'endiaStarman yup

ಠ_ಠ

El'endia Starman

Brilliantly executed, though.

3987^12 + 4365^12 = 4472^12

Is one still rick rolled if one closes the tab while the loading animation is still displayed, and there is no light or sound?

@Doorknob damnit

I was searching for that one

1:14 AM

@feersum One is ricked but insufficiently rolled

@orlp I knew the title :P

this is pretty rad

i.imgur.com/hR5J3Uo.gifv

Cᴏɴᴏʀ O'Bʀɪᴇɴ

whoa

El'endia Starman

Impressive.

@orlp Whoa. Is that you?

1:18 AM

@AlexA. eehm what

that video is clearly taken outside

of course it isn't me

Hahaha

Calvin's Hobbies

There's an outside now??

Cᴏɴᴏʀ O'Bʀɪᴇɴ

wait what

HI @QUARTATA

@Dennis please please don't be working on a Bubblegum flag of france

"Working"?

How do you work in Bubblegum

Anonymous

1:20 AM

Ruling question:

The computer instantly generates teh answer for you.

user image

Anonymous

Oh wait nvm the question answers it

> teh answer

@quartata If you can get to 38 bytes, I won't post mine.

1:21 AM

@Dennis Wow he's being so merciful

Thank you based golfer

> based golfer

Calvin's Hobbies

1:35 AM

Mini challenge: Put a string with two digits and one plus sign in the order [digit]+[digit]. e.g. 93+` 3+9 +93 would all become 9+3 or 3+9

@Calvin'sHobbies CJam, 6 bytes

Best! Golf! Evar!

codegolf.stackexchange.com/posts/64152/revisions

@Calvin'sHobbies Julia, 36 bytes: s->(m=matchall(r"\d",s))[1]*"+"*m[2]

@Dennis I can't even believe how many bytes you saved

Anonymous

@Calvin'sHobbies ,O'+O-W'+O+('+O-W@

Anonymous

18 bytes

@AlexA. I can't believe how I saved it. I hadn't made that mistake in a long time...

@Mego Seriously?

Anonymous

1:48 AM

@Dennis Not sure if dumbfounded or confirming language name

It works on many levels.

Anonymous

Wait I can do better :o

Calvin's Hobbies

@Dennis q = get all input, e! = get all unique permutations, -2 = -2, = = get index -2 of the permutations -> is this all correct?

Anonymous

,'+O-W'+O+('+O-W@

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@Calvin'sHobbies x=>x[0]+x[1]+x[2] JavaScript ES6 17 bytes

El'endia Starman

1:50 AM

$o2[1c"+"=3&1R]$O., 18 bytes.

Anonymous

17 bytes, I out-golfed Minkolang :P

Anonymous

Oh bugger that doesn't work

Anonymous

Still at 18

@Calvin'sHobbies Yes, that is correct. e! actually sorts the permutations, so it ignores the input order.

El'endia Starman

...sort! Oooh!

Calvin's Hobbies

1:51 AM

@Dennis ah, was just about to ask

Anonymous

Get input, explode into CP437 ordinals, push "+", explode, subtract top two, while truthy: add ordinal of "+" and rotate entire stack, swap top two

El'endia Starman

$os1R$O. 8 bytes!

Anonymous

It cycles through the stack until "+" is on top, then swaps the top two elements

Anonymous

Wait I'm dumb

Anonymous

,;'+=WX(;'+=W@

Anonymous

1:52 AM

Same idea, less bytes

El'endia Starman

*fewer

Anonymous

...I really need a sort command

@Calvin'sHobbies APL, 10 bytes: {¯1⌽⍵[⍋⍵]} try online

El'endia Starman

I BEAT APL! :D

Calvin's Hobbies

You beat Alex

El'endia Starman

1:54 AM

true

Calvin's Hobbies

AlexPL

CJam, 5 bytes

Calvin's Hobbies

How would one do ' '.join(someList) in cjam?

[list]S*

@Calvin'sHobbies In Julia, since you asked, it's join(someList, " ").

El'endia Starman

1:59 AM

Hmm. It'd be possible to do this task in three bytes with the right (possibly yet-to-exist) language: \rotateRight(\sort(\input( with implicit printing at the end.

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