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1:05 AM
Hello
 
user55340
@tnek316 'ello. As I mentioned a bit ago, weekends are a bit slow around here. But sometimes people look over to this window if they have it open.
 
@MichaelT Like I just did! :)
 
user55340
@AshleyNunn btw, Goblins webcomic has started updating again.
 
user55340
1:25 AM
btw, @AshleyNunn weird Canadian webcomic (not always safe for work... well, check out the first page if thats in doubt.... not at work) to look at butternutsquash.net/2003/04/16/meet-da-punks/2003/04/16/… (note, its 'completed' and signed off) ... another weird one by same artist that has taken a bit of a hiatus ( kukuburi.com/v2/2007/08/09/one )... though that one is SFW.
 
user55340
 
@MichaelT Yay!
@MichaelT I am intrigued by the first comic :)
 
user55340
@AshleyNunn keep clicking.
 
does
 
Yea I was just seeing if anyone was on
And if anyone on here could give some advice on a dilemma I'm having about creating a system?
 
user55340
1:32 AM
@tnek316 whats the question.
 
@MichaelT It is making me laugh. A lot. And I need that tonight :)
 
So I want to build a system that let's users upload music to a website
And being able to store that file and then eventually be called by mobile devices
And I don't really know how to set up the whole website system
So I was wondering if someone to point me in the right direction
 
user55340
You've got two types of things there - dynamic content (the 'search page results' and similar) and static content (the audio files). These are two different things that you'll want to serve separately because web servers that do static content don't do dynamic well, and app servers that do dynamic don't tend to do static well.
 
user55340
So you're going to find yourself with something like apache or nginx for static files. Download one of them, set it up, put files there, see how the file structure is.
 
user55340
Then you're also going to have an app server. Pick your preferred language and the appropriate app server... tomcat for java, node for javascript, mongrel for ruby, yaws for erlang... there's a bunch of them (that doesn't even scratch the surface).
 
user55340
1:43 AM
Write the program for the app server to store some information to a database so you can search that, and store the file to some place that can be accessed by the static server when uploaded.
 
Ok. So I will have a website with a interface that will upload the files to a web server(Apache)?
And then also store it to a app server?
 
user55340
Ultimately, you're going to have two web servers that share a common file system.
 
Ok. I think I at least have a starting point. Thank you. I was getting frustrated
 
user55340
That way also lets you scale each independently and if you find you need a content delivery network some day, it fits there too.
 
And then I will call to the server from the application?
 
user55340
1:47 AM
The web app 'lives' in the application server... its not something you download.
 
I meant from a mobile application
 
user55340
You could... lots of ways to design that. I'd first look at the 'just write a simple web app that uploads a file and lets you download it' - even in the same server instance (don't worry about dynamic vs static).
 
user55340
 
@MichaelT best kind of interlude.
 
user55340
 
1:51 AM
Ok thanks for the advice friend
 
@MichaelT hahaha that is excellent
 
 
2 hours later…
user55340
3:54 AM
@gnat @GlenH7 I've got a challenge for you... kill
 
2:14 PM
posted on September 22, 2014

Breaking the Complexity Barrier of Pure Functional Programs with Impure Data Structures by Pieter Wuille and Tom Schrijvers: Pure functional programming language offer many advantages over impure languages. Unfortunately, the absence of destructive update, imposes a complexity barrier. In imperative languages, there are algorithms and data structures with better complexity. We present our proj

 
2:55 PM
@GlenH7 so did you come up with a way to get your referential transparency? Did it help? :)
 
@MichaelT Did you get those shots you were after?
Also, anyone know of a good way to get a high current load out of an arduino? I think an OpAmp will do what I want, but I'm rubbish at OpAmps
I'm trying to drive some computer fans, so I think ~5 watts should do it with some room for overhead
 
user41796
@JimmyHoffa I placed the new call before the existing call. :-)
 
user41796
And since I wrote the new call I knew I would have idempotentancy. :-)
 
user41796
@Ampt You want to ask @whatsisname for that one. But yes, I think an opamp should do the trick. Or use another line out to trigger a relay and pull directly off the power supply
 
@GlenH7 I'd like to have it be an adjustable voltage level, which is why I can't just use this fancy relay shield I got
although it might come down to just having each of the 4 relays at a different voltage and then switching from one to the other
potential for a bad time if I get wires crossed though
but I've managed to get my arduino powered off of my PSU in my computer, so I've got that part down!
 
user41796
3:05 PM
Do you need continuous adjustment or just a couple of steps? You could simulate a couple of steps with just relays
 
Yeah, that's what I meant with the relays, each would be a different step
continuous adjustment wouldn't be totally necessary
but it would be cool
I'm also looking at upping to an arduino due to get more timer/counters so that I can track the feedback on each fan
it has 2 built in DAC but they're very low current
 
user41796
I have started asking myself "how much more would I be willing to pay to have XYZ" and I find more often than not I'm not willing to pay anything more and therefore it wasn't as important as I thought. :-)
 
haha well this is all being done to remove a lot of wire clutter in my case so I'm already far past my cost effective return lmao
 
user41796
ah, "educational opportunity" it is then
 
yes, lets go with that
besides, how cool would it be to have a custom fan controller for your computer
 
user41796
3:10 PM
erm.... :)
 
user41796
Then again, I have pondered the effort to setup a full DNP/IP telemetry solution for the various utilities on my house. Sooooo I'm not one to talk.
 
@GlenH7 well I've got 8 fans (so far) and only 4 motherboard headers for fans so... I need some room to grow
 
user41796
apparently...
 
user41796
that's one hella system you're growing there
 
I briefely considered leaving the path of watercooling after all the trouble I had getting my loop to fill properly, and then I plugged the two 780ti's in next to eachother and saw how little space I had between them
and watercooling suddenly made sense again.
@GlenH7 the arduino will also controller the LEDs I'm installing
so it's got another purpose as well
 
user41796
3:18 PM
@Ampt With a "do not disturb" window programmed into it as well?
 
@GlenH7 What do you mean by that? A time when the LEDs are off?
why would you ever turn them off?
 
user41796
I thought this was near where you were sleeping. And I had assumed the fan noise "issue" was because of it affecting sleep.
 
@GlenH7 Oh... well... the fans may or may not be completely silent on full blast
I just... want to turn them down?
I'm overengineering this aren't I.
 
user41796
it's your birthright.
 
user41796
9 mins ago, by GlenH7
Then again, I have pondered the effort to setup a full DNP/IP telemetry solution for the various utilities on my house. Sooooo I'm not one to talk.
 
3:23 PM
Alright, well at least I'm in good company when I decide that I'll need quadruple redundancy on an op amp haha
 
user41796
with as much hardware as they are protecting? Yeah...
 
Work is slow today so I am debating how much work it would be to attach a GPS tracking device to a recycling bin in a concealed sort of way. (I have had 4 recycling bins disappear on me since I have lived at my current place, and i am currently without a bin since it got stolen 4 weeks ago and I just get frustrated at the idea of getting a new one)
 
user41796
@AshleyNunn it's fairly trivial
 
How much would it cost?
(I have spent at least $40 on recycling bins.)
 
user41796
@AshleyNunn thetileapp.com
 
Oooh, options.
 
then you could get a GSM shield and log the data to the web
@AshleyNunn I'll admit that his is decidedly simpler
and probably cheaper
 
user41796
I haven't used their product, but it seems bog simple
 
user41796
@Ampt US$20 per tile, I think
 
I don't think it's actually real yet either
 
user41796
3:29 PM
free app & no programing
 
user55340
@Ampt Still working on 'em. For the sunset, I need the clouds to be right at sunset. Some clouds in the sky, but over the horizon it needs to be clear.
 
user41796
I thought they were shipping to pre-orders already, but I could be wrong.
 
user55340
There were also a number of them that I saw for just 'photos out there' along 54 that I need to look into more deeply.
 
@AshleyNunn also, who the hell is stealing your recycling bins?
 
@Ampt I don't know! But they keep disappearing! Even when labelled with my address.
 
3:31 PM
@AshleyNunn I vote you get a cheap pre-paid phone, conceal it in the bottom of the bin somehow and install an android tracking app
you'll be able to track it just about anywhere
 
user41796
@AshleyNunn I'm surprised they're not free. Cuts down on any theft problems and encourages more recycling
 
@GlenH7 Well, you get a certain number free per household from the city, but that is a limited number
and they cost at least $10 on sale at Canadian Tire
 
is that in.. canadian tire money?
 
user41796
@AshleyNunn But you get one free if you open a credit card today? :-P
 
user41796
(I get points for truly subtle humor)
 
3:33 PM
Do you have any old phones lying about?
 
@Ampt In real money :P
@Ampt Nope :(
 
:(
How about a baseball bat?
 
Nope. :(
I am useless
 
Not sure that the Tile system is going to do what you want
it looks like it's bluetooth only. once it's more than 150 feet away you're going to have a hard time finding it
 
Boo.
 
3:42 PM
bringing me back to point A - who the hell steals a recycling bin
 
user41796
Seriously...
 
user41796
Cra cra tree huggers...
 
@Ampt I have no idea! The first time it was just oh, maybe someone playing a weird prank, but it has happened so many times now that I just don't get it
 
I vote you chain them down to your hard with a 20 foot chain. should keep people from stealing them, while hopefully letting the garbage men empty them
my vote changes a lot, I know.
 
3:47 PM
I'd have to get permission from the upstairs pepole and I suspect that would be a sidewalk hazard.
I am however asking the WM people if they would have any reason to take the bin.
 
user41796
"people are nutters"
 
user41796
I was going to put a certain nationality in there, but realized by pointing a finger I was merely pointing several more back my way...
 
user41796
But for the record, I overengineer the heck out of things. I don't go around stealing recycling bins.
 
Everyone I know is like "why is this happening to you, no one steals bins" and I am like "wish I knew". Like it is a completely unheard of thing, especially 4 times!
 
yeah. we're people of principal. people who like solutions more complicated than the problems they solve. people who will go out of their way to make sure that every possibly contingency, up to and including the sun going out, are met, so that our gardens can be watered on time, or our lights go off when they're supposed to!
 
3:54 PM
@GlenH7 people are dicks.
politics aside, that's just basically the definition of being an asshole
 
Python list comprehensions make my brain kinda hurt
 
@Ampt Hey, if that sort of solution means I keep my bin, I am game.
 
@AshleyNunn I'm working on a solution with quadracopters and scheduling patrols of the neighborhood. give me a second.
 
@Ampt oh? what's confusing about them? I could give you a simple rewriting rule that turns them into something SQL-like if it made more sense to you that way
 
user55340
low power bluetooth thing that recognizes when its out of the radius of a given bluetooth device. When it gets out of range, have it play a very loud tone/air horn.
 
3:58 PM
I'm getting them, and they're doing what I want
 
@Ampt I like where this is headed
 
it just takes me a second to think my way through em.
 
@MichaelT This is also good.
 
How much do you think a standard issue anvil weighs?
 
user55340
Kind of like those things they put on the wheels of shopping carts to prevent them from getting taken off premises... but with more sound.
 
user41796
3:59 PM
@Ampt They range in size. Decent ones ought to clock in at 50lbs or so anvilfire.com/21centbs/Selecting-an-Anvil.php
 
user55340
(poking about on Reddit some... /r/java is having their "we're fed up with September here" post and working to enforce their scope: reddit.com/r/java/comments/2h41yx/… )
 
The question quality on SO is just terrible this morning.
 
user41796
@RobertHarvey Can you temporarily halt all questions?
 
user41796
"SO is closed for questions due to the insane amount of crap that has already been posted today."
 
Wouldn't that be cool.
 
user55340
4:04 PM
Set up an auto close bot... point it at android, php...
 
user41796
And the resulting MSO explosion would be epic
 
user55340
anything that isnt tagged with a language...
 
user41796
Or just protect the whole site - you have to have earned at least 10 rep to ask a question
 
user55340
Put in a feature request for tag protection.
 
user41796
"Hey, we can't tolerate any more of your crap at the moment. We'll open the doors back up once we've got this pile cleaned up..."
 
user55340
4:05 PM
"No new questions until the close review queue is less than 1000"
 
@GlenH7 So if I can get .5 pounds of thrust per prop... I'm going to need some jet engines.
 
1
Q: How closely related are the difference lists from functional and logic programming?

Steve314Both functional and logic programming have a common idiom called "difference lists". The meaning seems to be different in each case, yet at the core the same thing. Key points... The idea is always to leave a "hole" in an immutable list to be filled in later. The "hole" always consists of a cur...

^-- feel free to CV. this question really has no...question...
 
user55340
btw, I answered a SO question this weekend... found what I think is a bug in gcc.
 
user55340
5
A: Better compiler warnings?

MichaelTThe option you are after is likely -Wmaybe-uninitialized or -Wuninitialized. Both of these are part of the -Wall option which turns on these, and many other warnings (the -Wxxx options are related to warnings). Full documentation of the warning options for gcc may be read at: Options to Request...

 
"how closely related are ...." cannot an answerable question make.
 
4:06 PM
Seems like a lot of people just want to start discussions this morning.
 
he delineates the differences in his question himself, so an answer that describes the differences doesn't answer him. He just wants a discussion.
 
user55340
@RobertHarvey I would contend that SO needs at least one hard nosed mod...
 
now we're cooking
 
user41796
@Ampt grainger
 
user55340
(Though I'll give Andrew a bit of credit for closing all the rest of the questions after a rollback war I flagged)
 
4:08 PM
@GlenH7 Not that kind of jet.
 
user41796
@Ampt honeywell, GE, ?
 
Doesn't really fit here - there's no answer to be had, just a discussion. Feel free to have discussions in The Whiteboard our official discussion room. I voted to close vote though as I don't see a possible answer to "how closely related are ...." - within an inch? a year? there's no metric for such. — Jimmy Hoffa 30 secs ago
 
user41796
pretty sure raytheon won't sell to the general public. Dunno about lockheed
 
user55340
One of the net bits with that compiler question was finding gcc.godbolt.org
 
4:09 PM
Well, it's turbo prop
but you get the gist
we just need 27" props
 
user55340
Click the 'clourise' button on that one.
 
but with 4 we should be able to haul fuel and a decent sized anvil
 
user41796
@Ampt I love engineers
 
I would think that the HOA would disapprove of anvil armed quadcopters buzzing around the neighborhood, but lets be honest, who the hell is going to mess with someone backed by an army of anvil-dropping mechanical monsters.
 
user55340
@Ampt They just don't want Amazon and Google to take over the left coast.
 
user41796
4:11 PM
And the HOA will realize that they are hunting down recycling bin stealers. And honestly, if there isn't a better way to deal with them than Acme brand anvils dropped on their heads then I don't know what to say.
 
user55340
Between self driving cars and drone delivery... you're not that far from Terminator Judgement day.
 
user41796
skynet domain registered?
 
user55340
I'm sure sky.net is, and likely skynet.com too.
 
user55340
Oh, wouldn't that have been a domain name to grab in the early days... "sky.net"
 
@Ampt Waiting for the day when we start seeing gun owners playing skeet with the quadcopters.
 
4:14 PM
@RobertHarvey I'm thinking it's going to be a while until that's cost effective
 
The skeet, or the quadcopters?
 
user41796
@Ampt buckshot is pretty cheap...
 
We are talking about shooting the quadcopter right?
 
Yep. People will claim it's in their airspace. And they would probably be right.
 
you don't own above X feet in your yard actually.
that belongs to the US Gov
same with below.
 
4:16 PM
It's something like above 500 feet. Give or take a few hundred.
 
hi guys
 
Are you with the government?
 
We're all women here.
 
we swear, it's not what it looks like.
 
hi girls
 
4:17 PM
We're packing, so watch what you say.
 
Anvils to be specific.
 
So, the WM people told me the people picking up the recycling wouldn't take the bin ever, so someone is obviously messing with me :(
 
(Yes, this is the programming room)
 
user41796
@AshleyNunn 140 dB siren ought to solve that problem
 
honestly I would think just mounting a camera somewhere that has a veiw of the recycling cans would work.
 
4:18 PM
someone said my name?
 
user41796
put your bin out; put the siren on a 10 hour timer. Come home, and wait for a few hours for it to go off.
 
@GlenH7 If I could get it so it wouldn't go off when I brought the bin in/out or the pick up people were doing their job, then yes
 
@whatsisname HA! You've activated my trap card!
 
user41796
@whatsisname @Ampt needs help with figuring out how to power the fans on his rig
 
@Ampt There is a tree there, but I would have no idea what to do. I guess a trail cam might work, although I live on a busy street so it would go off a lot
 
user41796
4:19 PM
@AshleyNunn exactly, that's what the timer is for. If you get it back in time, you deactivate the timer.
 
I'd like to go from low amperage analog signal to high amperage one. something like 5 watts @12V
 
to power a fan?
 
user41796
And note that anything > 120 dB has the potential to immediately induce vomiting
 
multiple fans
they're 120mm computer fans.
 
when you say an analog signal are you expecting speed control?
 
4:20 PM
@Ampt flying anvil monsters? Sounds like the job for an Italian plumber to me.
 
@whatsisname yep!
 
you'll have to PWM them
 
I was thinking PWM with a low pass analog filter, but the arduino I was looking at actually has DAC channels
 
user41796
@whatsisname Is that because they simply won't turn on at a lower voltage?
 
forget the filter, the fan won't spin unless the voltage is above something like 6 or 7 volts for a 12v fan
 
4:22 PM
Yeah, but I can get them spinning at higher voltage and then bring them down, no?
 
user41796
@whatsisname that makes sense then why you need PWM
 
they have feedback sensors, so I can sense when they're stopped
 
maybe, but I doubt it
just PWM them and save yourself the trouble
 
They're dual ball bearing fans. pretty low resistance
 
its not a resistance thing, its because the fans are brushless DC motors
brushless motors are essentially AC motors, with fancy electronics to do the switching instead of mechanical brushes
 
user41796
4:24 PM
@Ampt you still need some amount of force to overcome the motors inertial resistance
 
@GlenH7 yeah, but once they're spinning I should be able to back off, no?
 
if you really want to have an analog out, then use a comparator to turn that into a PWM signal instead of with your MCU
 
they typically aren't controlled with PWM though
they make PWM fans
these are not those
 
Ampt, you might be able to back them off, but they will likely just turn off once you get below a certain voltage threshold
computer fans have really cheap crappy motors and controllers in them
you can either PWM it and have it working properly right away
or have some complicated analog control that will be dodgy and require lots of tweaking to get it going
your call
 
user41796
@whatsisname he's an engineer and you just sniped him with a crappy option. Props!
 
4:28 PM
Ok, so how am I going to get a PWM signal with enough power to turn the fans?
the atmel chips aren't exactly high power
I think I get 20mA per line
@5V
 
no MCU has enough power to drive fans with its IO pins
you'll connect your IO line to a transistor
 
user41796
@Ampt Not necessarily. The inertial resistance comes from the physical friction of the parts as well as the magnetic field that the motor is sitting within. The physical friction aspect will drop off once spinning but the magnetic field won't. And I'm willing to bet the magnetic field resistance is much greater than the physical friction
 
to switch the fan on and off
 
It's lunch here, I'll think about it and get back to you
I hear that the PWM actually makes the fan louder... are we sure that a filter is off the table?
 
you can use either a BJT or a FET
 
user41796
4:31 PM
@whatsisname I'm assuming pretty much any kind of transistor and just push it into saturation for the on portion? So use it like an on / off switch and not as an amplifier?
 
yeah basically
 
user41796
@Ampt If the only source of noise is the fan itself, how would using PWM make it louder?
 
user41796
there shouldn't be any on / off switching noise within the fan itself
 
I don't know if the PWM would make the fan louder but I wouldn't be surprised
 
user55340
btw, @GlenH7 looking for two more 20k delete votes in programmers.stackexchange.com/questions/76666/…
 
4:33 PM
as I mentioned, brushless DC motors are AC motors with integrated inverters/switching electronics
 
user41796
@MichaelT gone
 
if you are PWMing it, there could be some aliasing which could create some noise
 
user41796
that makes sense
 
which is why I originally wanted to do a filter, but then I figured if I was doing that, I might as well go all the way with a DAC
 
user41796
so the next achievement to unlock is making the fans "sing" a song by controlling the speed of the PWM
 
4:35 PM
The only song I want is silence!
 
motor control is a vast subject unto itself
 
user41796
 
I'm just trying to make the fans quiet
I'd like to bring down the RPM in hopes of getting them to be quieter
 
user55340
@Ampt You just need louder fans to make it seem like yours are quiet. Try using it at a sporting event.
 
@MichaelT I want this thing to be like a golf tournament.
 
user41796
4:39 PM
You can be bolder than that.... C'mon now
 
@Ampt Is this for a PC? Most motherboards already have fan control, and if you're using a liquid-cooled radiator, the fans that go with those things are capable of turning very slowly for quiet.
 
by adjusting your pwm frequency you should be able to get the fans plenty quiet
 
@GlenH7 better?
 
user55340
You could put a speaker on there that plays the noise cancelation sound...
 
user41796
@Ampt Sooooooooooooooo boring....
 
user41796
4:40 PM
@MichaelT Oh, that's brilliant
 
@RobertHarvey Have: Mobo with 4 fan headers, 8 fans Need: 8 fans controller
 
user55340
@GlenH7 don't tempt me...
 
user55340
The Unix banner program outputs a large ASCII art version of the text that is supplied to it as its program arguments. One use of the command is to create highly visible separator pages for print jobs. == Operation == Each argument is truncated at 10 characters and printed on a "line" of its own. To print multiple words on a single line, they must therefore be passed as a single argument, which is done from the shell by escaping or quoting the words as appropriate. A related and more flexible program is FIGlet, which can display text in different fonts and orientations. == Implementation == The...
 
user41796
There's 8 fans, so you ought to be able to synchronize them so their noise cancels each other out
 
8 fans? For the love of mike, why?
 
user41796
4:41 PM
@RobertHarvey He's an engineer
 
@RobertHarvey 6 are for the radiators, 2 are just general airflow
@GlenH7 also yes.
 
user55340
@RobertHarvey He'd have more than ${NFL player in trouble with the law}...
 
user41796
My answer was more apt and succint. :-)
 
A proper water cooling system should need two fairly large fans, and that's it. The power supply fan takes care of the general airflow.
 
@RobertHarvey it's got an overclocked i5 and 2x780tis on the same loop
so it's gotta dissipate ~600 watts
 
4:42 PM
Yes. Two fans.
 
user41796
all that for an i5?!
 
user55340
I wonder if you could build a hovercraft with PC fans... discovery.com/tv-shows/mythbusters/videos/…
 
@GlenH7 Almost doesn't seem worth it, does it?
 
@GlenH7 shutup. it's overclocked
@MichaelT they can't even lift their own weight, so no.
 
anyways @Ampt if you wanna ignore my claims that you need to PWM it then go ahead, but either way you don't need an op-amp, just some transistors
 
4:43 PM
@whatsisname It's not ignoring it's more of selective hearing
@GlenH7 it's a 2500k @ 4.5 ghz so it's still decently fast
 
Any liquid-cooled system worth its salt should already have the necessary controllers, either on the mobo, or in the cooling system itself.
 
Not worth upgrading to the new haswell-e until they get the ddr4 production in line. 600+ for 16 gigs of ram
it's reidiculous
@RobertHarvey what do you mean by liquid cooled? Are you talking about these all-in-one solutions?
mine is a custom loop
 
user41796
@whatsisname he's definitely not ignoring you. We're prone to hashing things to death in here. Pretty much typical for a bunch of engineers. :-)
 
lol
 
4:46 PM
 
user55340
@GlenH7 md5(sha1("death")); // ?
 
user41796
@ampt Is the fish tank filled with mineral spirits still ruled out?
 
user41796
@MichaelT I prefer more elegant hashing algorithms, but yeah. :-)
 
user55340
@GlenH7 You need to do it twice to hash it to death...
 
@GlenH7 I wouldn't say it's completely off the table
Yeah no, that's definitely not what I'm using @robertharvey
 
user41796
4:52 PM
Just failed a review audit. So I looped back around and made sure that would never happen again. :-)
 
@GlenH7 Back in the day when you could put music to any kind of moving imagery and call it a video.
 
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