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  • efficiently determining if a polynomial has a root in the interval [0,T]

    - by user168715
    I have polynomials of nontrivial degree (4+) and need to robustly and efficiently determine whether or not they have a root in the interval [0,T]. The precise location or number of roots don't concern me, I just need to know if there is at least one. Right now I'm using interval arithmetic as a quick check to see if I can prove that no roots can exist. If I can't, I'm using Jenkins-Traub to solve for all of the polynomial roots. This is obviously inefficient since it's checking for all real roots and finding their exact positions, information I don't end up needing. Is there a standard algorithm I should be using? If not, are there any other efficient checks I could do before doing a full Jenkins-Traub solve for all roots? For example, one optimization I could do is to check if my polynomial f(t) has the same sign at 0 and T. If not, there is obviously a root in the interval. If so, I can solve for the roots of f'(t) and evaluate f at all roots of f' in the interval [0,T]. f(t) has no root in that interval if and only if all of these evaluations have the same sign as f(0) and f(T). This reduces the degree of the polynomial I have to root-find by one. Not a huge optimization, but perhaps better than nothing.

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  • Grouping timestamps by interval between timestamps, then calculating from group MySQL

    - by Emile
    To put this question into context, I'm trying to calculate "time in app" based on an event log. Assume the following table: user_id event_time 2 2012-05-09 07:03:38 3 2012-05-09 07:03:42 4 2012-05-09 07:03:43 2 2012-05-09 07:03:44 2 2012-05-09 07:03:45 4 2012-05-09 07:03:52 2 2012-05-09 07:06:30 I'd like to get the difference between the highest and lowest event_time from a set of timestamps that are within 2 minutes of eachother (and grouped by user). If a timestamp is outside of a 2 minute interval from the set, it should be considered a part of another set. Desired output: user_id seconds_interval 2 7 (because 07:03:45 - 07:03:38 is 7 seconds) 3 0 (because 07:03:42) 4 9 (because 07:03:52 - 2012-05-09 07:03:43) 2 0 (because 07:06:30 is outside 2 min interval of 1st user_id=2 set) This is what I've tried, although I can't group on seconds_interval (even if I could, I'm not sure this is the right direction): SELECT (max(tr.event_time)-min(tr.event_time)) as seconds_interval FROM some_table tr INNER JOIN TrackingRaw tr2 ON (tr.event_time BETWEEN tr2.event_time - INTERVAL 2 MINUTE AND tr2.event_time + INTERVAL 2 MINUTE) GROUP BY seconds_interval

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  • HP Laserjet "maintenance interval" vs "fuser life"

    - by marienbad
    I posted a question about the Laserjet 8100DN earlier here: http://serverfault.com/questions/139043/buying-an-old-laser-printer-what-will-need-to-be-replaced and from doing some more research I have a new question: I found the "maintence interval" -- "the interval at which you should install a maintenance kit" (which is a fuser and rollers), and it is...350,000 pages. BUT, when I look at the specs for an HP 8100 fuser, it says the fuser has a life span of 150,000 pages. What gives? – Will the fuser go bad after 150 or 350? ==== BTW I hope it's ok to ask another similar question in a new thread -- I'm just following instructions from my thread on the topic at Meta.

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  • Linear regression confidence intervals in SQL

    - by Matt Howells
    I'm using some fairly straight-forward SQL code to calculate the coefficients of regression (intercept and slope) of some (x,y) data points, using least-squares. This gives me a nice best-fit line through the data. However we would like to be able to see the 95% and 5% confidence intervals for the line of best-fit (the curves below). What these mean is that the true line has 95% probability of being below the upper curve and 95% probability of being above the lower curve. How can I calculate these curves? I have already read wikipedia etc. and done some googling but I haven't found understandable mathematical equations to be able to calculate this. Edit: here is the essence of what I have right now. --sample data create table #lr (x real not null, y real not null) insert into #lr values (0,1) insert into #lr values (4,9) insert into #lr values (2,5) insert into #lr values (3,7) declare @slope real declare @intercept real --calculate slope and intercept select @slope = ((count(*) * sum(x*y)) - (sum(x)*sum(y)))/ ((count(*) * sum(Power(x,2)))-Power(Sum(x),2)), @intercept = avg(y) - ((count(*) * sum(x*y)) - (sum(x)*sum(y)))/ ((count(*) * sum(Power(x,2)))-Power(Sum(x),2)) * avg(x) from #lr Thank you in advance.

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  • How do i convert from milliseconds to seconds units to be shown in a Label?

    - by Doron Muzar
    I have this code: private void Form1_MouseWheel(object sender, MouseEventArgs e) { if (leave == true) { if (e.Delta > 0) { if (timer1.Interval < 5000) { timer1.Interval += 1000; label2.Text = (timer1.Interval/1000).ToString(); } } else { if (timer1.Interval == 1000) { timer1.Interval -= 100; label2.Text = (timer1.Interval / 1000).ToString(); } } } } The original timer1 interval in the designer is set to 1000 milliseconds. In the mouse wheel event i did that it will show in the label2 the untis in seconds. And indeed when i move the mouse wheel up its slowing the timer and show it in seconds 1 2 3 4 5 The problem is with the second part i wanted that when its getting to 1 second or 1000 milliseconds if i will keep wheel it down it will show the units in 100 and change the timer1.interval in 100 units. So in label2 if it was on 1 second so now i will see 900 800 700 600 500 un till 100. And also the timer1 interval should be change to 900 milliseconds 800 700 600 untill 100. When its get to 100 just stop there dont keep getting under 100. The problem is with this part: if (timer1.Interval == 1000) { timer1.Interval -= 100; label2.Text = (timer1.Interval / 1000).ToString(); } Its not working at all. EDIT** My code now: if (leave == true) { if (e.Delta > 0) { if (timer1.Interval < 5000) { timer1.Interval += 1000; label2.Text = (timer1.Interval / 1000).ToString(); } } else { if (timer1.Interval > 1000) { timer1.Interval -= 1000; label2.Text = (timer1.Interval / 1000).ToString(); } else if (timer1.Interval <= 1000 && timer1.Interval > 100) { timer1.Interval -= 100; label2.Text = (timer1.Interval / (double)1000).ToString(); } } } But now if i was at 5 seconds(5000 milliseconds) now i move the wheel back down its counting 5 4 3 2 1 0 and stop on 0 It dosent show under 1 ...0.9 0.8 0.7 as it did before.

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  • How can I dispatch an PropertyChanged event from a subscription to an Interval based IObservable

    - by James Hay
    I'm getting an 'UnauthorizedAccesExpection - Invalid cross-thread access' exception when I try to raise a PropertyChanged event from within a subscription to an IObservable collection created through Observable.Interval(). With my limited threading knowledge I'm assuming that the interval is happening on some other thread while the event wants to happen on the UI thread??? An explanation of the problem would be very useful. The code looks a little like: var subscriber = Observable.Interval(TimeSpan.FromSeconds(1)) .Subscribe(x => { Prop = x; // setting property raises a PropertyChanged event }); Any solutions?

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  • Show and hide divs at a specific time interval using jQuery

    - by Webrsk
    I would like to show divs at a specific interval (10 seconds) and show next div and as go on and repeat the same. ** Sequence : ** On 10th second show div1 , hide other divs , After 5seconds interval Show div 2 and hide other divs, After 5 seconds interval Show div 3 and hide other divs, and repeat the same for every 10 seconds. Code Follows: <div id='div1' style="display:none;"> <!-- content --> </div> <div id='div2' style="display:none;"> <!-- content --> </div> <div id='div3' style="display:none;"> <!-- content --> </div>

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  • Behaviour of System.Timer when Interval property changed

    - by lowlyintern
    I have a System.Timer setup to trigger an event every day at 2AM. If the process the timer starts fails then I want the timer to be reset to run every 15 minutes until the process completes succesfully. // this is how the timer is set up. // this is working correctly. double startTime = milliseconds_of_hour_to_start. Timer = new System.Timers.Timer( startTime); Here is the code to reset the timer on success or failure of the event handler. NOTE the timer is not being stopped, just the Interval property is being reset. if (ProcessSuccess) { Timer.Interval = TimeSpan.FromHours(24).TotalMilliseconds; } else { Timer.Interval = TimeSpan.FromMinutes(15).TotalMilliseconds; } My question is this, if the process fails say 4 times, then succeeds will the Timer now be running at around 3AM? i.e. after failing will the original start time of 2AM be advanced by 15 minutes?

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  • Finding records within a 5 min time interval in SQL

    - by Mellonjollie
    I have a table with over 100,000 rows that contain the following columns: ID, Time, and Boolean. The time column tracks time down to the second. I need a query that will find all instances of Boolean = 1 for every 5 minute interval of time from the start of the table to the end, then group the count by time interval. The table represents 4 hours of data, so I should get 48 rows of results. I'm using MS SQL Server. I've tried a few approaches, but the time interval logic is giving me a hard time.

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  • Darwin Streaming Server Interval Role

    - by Asmv9
    I want to use the Interval Role in Darwin streaming server,more specifically i want to call the QTSS_SetIntervalRoleTimer() when the server starts streaming a video file.But i have problem in doing this as from what it seems,the method returns QTSS_Err when i do that. I believe that the problem is due to the fact that the callback is made in a a module-created thread. Is there a specific place where this callback must be done?(if i put the callback in the register role of my module it works,but i dont want this,because i dont want the timer starting when the server starts).Any help will be useful,thank u in advance.

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  • Managing the interval for horizontal axis in flex

    - by Roshan
    Hi Guys, How can we manage the horizontalaxis interval in flex chart? What actually happening is , the data is inserted between two interval levels and its causing readability problem when we draw line grids in graph. The data point is shown in between the data grids. How can we move the axis or manage the data points?

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  • Haskell newbie on types

    - by garulfo
    I'm completely new to Haskell (and more generally to functional programming), so forgive me if this is really basic stuff. To get more than a taste, I try to implement in Haskell some algorithmic stuff I'm working on. I have a simple module Interval that implements intervals on the line. It contains the type data Interval t = Interval t t the helper function makeInterval :: (Ord t) => t -> t -> Interval t makeInterval l r | l <= r = Interval l r | otherwise = error "bad interval" and some utility functions about intervals. Here, my interest lies in multidimensional intervals (d-intervals), those objects that are composed of d intervals. I want to separately consider d-intervals that are the union of d disjoint intervals on the line (multiple interval) from those that are the union of d interval on d separate lines (track interval). With distinct algorithmic treatments in mind, I think it would be nice to have two distinct types (even if both are lists of intervals here) such as import qualified Interval as I -- Multilple interval newtype MInterval t = MInterval [I.Interval t] -- Track interval newtype TInterval t = TInterval [I.Interval t] to allow for distinct sanity checks, e.g. makeMInterval :: (Ord t) => [I.Interval t] -> MInterval t makeMInterval is = if foldr (&&) True [I.precedes i i' | (i, i') <- zip is (tail is)] then (MInterval is) else error "bad multiple interval" makeTInterval :: (Ord t) => [I.Interval t] -> TInterval t makeTInterval = TInterval I now get to the point, at last! But some functions are naturally concerned with both multiple intervals and track intervals. For example, a function order would return the number of intervals in a multiple interval or a track interval. What can I do? Adding -- Dimensional interval data DInterval t = MIntervalStuff (MInterval t) | TIntervalStuff (TInterval t) does not help much, since, if I understand well (correct me if I'm wrong), I would have to write order :: DInterval t -> Int order (MIntervalStuff (MInterval is)) = length is order (TIntervalStuff (TInterval is)) = length is and call order as order (MIntervalStuff is) or order (TIntervalStuff is) when is is a MInterval or a TInterval. Not that great, it looks odd. Neither I want to duplicate the function (I have many functions that are concerned with both multiple and track intevals, and some other d-interval definitions such as equal length multiple and track intervals). I'm left with the feeling that I'm completely wrong and have missed some important point about types in Haskell (and/or can't forget enough here about OO programming). So, quite a newbie question, what would be the best way in Haskell to deal with such a situation? Do I have to forget about introducing MInterval and TInterval and go with one type only? Thanks a lot for your help, Garulfo

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  • script to count the occurence of the particular string in the given time interval

    - by pruthvi
    We are trying to write a script "sendemail.sh" to count the number of occurrence of a particular string in a log file "SendEmail.log" within the given interval. We have a log file. In that we are searching for a pattern "ReqInputMsgLog" and need to count the number of times it occurred in the given period for eg: from "2014-08-19 11:30" to "2014-08-19 11:34". And our script look like this: #!/bin/sh enterdate=$1 echo $enterdate enddate=$2 enterdate1=`date +%s -d $enterdate +"%Y-%m-%d %H:%M"` echo $enterdate1 enddate1=`date +%s -d $enddate +"%Y-%m-%d %H:%M"` echo $enddate count=0 cat SendEmail.log | grep "ReqInputMsgLog" | awk -F "[" '{print $3}' | awk -F "," '{print $1}' > /con/scripts_server/file.txt for line in `cat /con/scripts_server/file.txt` do logdate=`echo $line | awk -F : '{print $1":"$2}'` if [[ $logdate < $enddate1 ]]; then count=`expr $count + 1` fi done echo $count But when we are trying to execute the script by the below command its not showing the proper count. ./sendemail.sh "2014-08-19 11:30" "2014-08-19 11:34" Log file is very big one. Small chunk has been posted here. INFO [SIBJMSRAThreadPool : 5] [2014-08-19 11:18:24,471] SendEmail - 8/19/14 11:18 AM,ECCF25B0-0147-4000-E000-1B830A3C05A9,ReqInputMsgLog,SendEmail,<?xml version="1.0" encoding="UTF-8"?> <in:sendEmailRequestMsg xmlns:in="http://EmailMed/EmailMedInterface" xmlns:ns0="wsdl.http://EmailMed/EmailMedInterface" xmlns:ns1="http://EmailMed/EmailMedInterface" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:me="wsdl.http://EmailMed/EmailMedInterface" xsi:type="me:sendEmailRequestMsg"> <in:sendEmail xmlns:xci0="http://EmailMed/EmailMedInterface"> INFO [SIBJMSRAThreadPool : 7] [2014-08-19 11:18:14,235] SendEmail - 8/19/14 11:18 AM,ECCEFDB2-0147-4000-E000-1B830A3C05A9,ReqInputMsgLog,SendEmail,<?xml version="1.0" encoding="UTF-8"?> <in:sendEmailRequestMsg xmlns:in="http://EmailMed/EmailMedInterface" xmlns:ns0="wsdl.http://EmailMed/EmailMedInterface" xmlns:ns1="http://EmailMed/EmailMedInterface" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:me="wsdl.http://EmailMed/EmailMedInterface" xsi:type="me:sendEmailRequestMsg"> <in:sendEmail xmlns:xci0="http://EmailMed/EmailMedInterface"> INFO [SIBJMSRAThreadPool : 7] [2014-08-19 11:18:14,241] SendEmail - xmlText: <?xml version="1.0" encoding="UTF-8"?> after awk command we will get a file "/con/scripts_server/file.txt" which looks similar like below: 2014-08-19 11:28:03 2014-08-19 11:28:06 2014-08-19 11:28:17 2014-08-19 11:28:53 2014-08-19 11:29:02 2014-08-19 11:29:47 2014-08-19 11:29:57 2014-08-19 11:30:07 2014-08-19 11:30:17 2014-08-19 11:30:19 2014-08-19 11:30:19 2014-08-19 11:30:22 2014-08-19 11:30:25 2014-08-19 11:30:25 2014-08-19 11:30:36 2014-08-19 11:30:51 2014-08-19 11:30:56 2014-08-19 11:30:59 2014-08-19 11:30:59 2014-08-19 11:31:08 2014-08-19 11:31:25 2014-08-19 11:32:19 2014-08-19 11:32:22 2014-08-19 11:32:27 2014-08-19 11:32:28 2014-08-19 11:32:41 2014-08-19 11:32:49 2014-08-19 11:32:59 2014-08-19 11:33:27 2014-08-19 11:33:41 2014-08-19 11:34:07 2014-08-19 11:34:14 2014-08-19 11:34:21 2014-08-19 11:34:25 2014-08-19 11:34:38 2014-08-19 11:34:50 2014-08-19 11:34:58

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  • Interval arithmetic to correctly deal with end of month - Oracle SQL

    - by user2003974
    I need a function which will do interval arithmetic, dealing "correctly" with the different number of days in a month. For my version of "correctly" - see below! First try select to_date('31-May-2014') + interval '1' months from dual This returns an error, because there is no 31st June. I understand that this behaviour is expected due to the ANSI standard. Second try select add_months(to_date('31-May-2014'),1) from dual This correctly (in my use case) returns 30th June 2014, which is great. BUT select add_months(to_date('28-Feb-2014'),1) from dual returns 31st March 2014, when I want 28th March 2014. Background This has to do with legal deadlines. The deadlines are expressed in law as a number of months (say, 3) from a base date. If the base date is last day of the month and three months later the month is longer, then the deadline does NOT extend to the end of the longer month (as per the add_months function). However, if the base date is last day of the month and three months later the month is shorter, then the deadline expires on the last day of the shorter month. Question Is there a function that does what I need? I have intervals (year to month) stored in a table, so preferably the function would look like: add_interval_correctly(basedate DATE, intervaltoadd INTERVAL YEAR TO MONTH)

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  • How to provide a date variable an interval that consists of an integer variable in Postgresql

    - by Lucius Rutilius Lupus
    I am trying to extract an amount of years from a specific date for this the correct syntax is <date> - interval '5 years'; But I dont want to extract a specific amount of years but a variable, which user will provide as a parameter. I have tried the following the variable name is years : date+interval '% years',years; I am getting an error and it doesn't let me do it that way. What would be the right way to do it.

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  • mysql error in query for timestamp interval

    - by nik parsa
    I have voting_IP table as follow: +-----------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+----------------+ | ip_id | int(11) | NO | PRI | NULL | auto_increment | | mes_id_fk | int(11) | YES | MUL | NULL | | | ip_add | varchar(40) | YES | | NULL | | | timestamp | datetime | YES | | NULL | | +-----------+-------------+------+-----+---------+----------------+ I want to run this query which has errors and I don't know how to correct it? $ip_sql=mysql_query("select ip_add from Voting_IP where mes_id_fk='$id' and ip_add='$ip' and timestamp > (DATE_ADD(now(), INTERVAL -1 HOUR);)"); I also tried this one: $ip_sql=mysql_query("select ip_add from Voting_IP where (mes_id_fk='$id' and ip_add='$ip' and timestamp > (DATE_ADD(now(), INTERVAL -1 HOUR);))");

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  • Can we change dynamically the interval of "schedule" ?

    - by micropsari
    Hello, I'm making a game on iPhone using cocos2d, and I have a question. In my init method I'm doing this : [self schedule:@selector(newMonster:) interval:1]; It create a new monster every second. But I'd like that the interval change over time. For example : -The 10 first seconds of the game: a new monster appears every 1 second. -Then for 10 seconds: a new monster appears every 0.8 second. -And after every 0.5 second... How can I do that? Thanks !

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  • C# timer getting fired before their interval time

    - by Swati Ghaisas
    Hi, We're getting following problem while using system.threading.timer ( .net framework 2.0 ) from a Windows service. There are around 12 different timer objects.. Each timer has due time and interval. This is set correctly. It is observed that after 3 to 4 hours, the timers start signalling before their interval elapses. For example if the timer is supposed to signal at 4:59:59, it gets signalled at 4:59:52, 7 seconds earlier. Can someone tell me what is the cause for this behavior and what is the solution for that ? Thanks, Swati

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  • Converting a constantly changing scalar value to a changing interval or frequency

    - by eco_bach
    Although I'm coding in Objective C, this is more of a general programming question. What is the best way to convert a constantly changing scalar value to a changing interval or frequency? Right now every time the scalar value changes I am destroying the NSInterval ie [self.myTimer invalidate]; self.myTimer = nil; and creating a new one, but this seems like a VERY expensive way to achieve my goal, since the changing scalar value in my case represents the horizontal velocity of a swipe. For a rough analogy, think of the speed of a swipe being reflected in a visual metronome, the faster you swipe, the higher(shorter interval) the frequency of the metronome.

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  • GUVCVIEW errors

    - by Brian Snapp
    I had GUVCVIEW working once before. it suddenly quit working. This is the error I receive........ bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) video device: /dev/video0 /dev/video0 - device 1 Init. Intergrated Webcam (location: usb-0000:00:1a.7-2) { pixelformat = 'YUYV', description = 'YUV 4:2:2 (YUYV)' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1024, height = 768 } Time interval between frame: 1/9, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/9, 1/5, checking format: 1196444237 Format unavailable: 1196444237. Init v4L2 failed !! Init video returned -2 trying minimum setup ... video device: /dev/video0 /dev/video0 - device 1 Init. Intergrated Webcam (location: usb-0000:00:1a.7-2) { pixelformat = 'YUYV', description = 'YUV 4:2:2 (YUYV)' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1024, height = 768 } Time interval between frame: 1/9, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/9, 1/5, checking format: 1448695129 Requested Format unavailable: get width 640 height 480 vid:0c45 pid:6410 driver:uvcvideo (guvcview:4079): Gtk-CRITICAL **: gtk_hscale_new_with_range: assertion `min < max' failed (guvcview:4079): Gtk-CRITICAL **: gtk_scale_set_draw_value: assertion `GTK_IS_SCALE (scale)' failed Segmentation fault I suppose the problem lies in the fact, that I cannot locate a configuration file to edit. Any help in where this file may lie? I have tried searching for any/everything related to guvcview, and have had zero success. Thank you for taking the time to read this, and hopefully providing a solution..

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  • obj-c : iphone programming NSTimeInterval problem

    - by the1nz4ne
    hi, i got a problem with my time interval. I need to get the interval of two times in this format : HH:MM. If i enter : 15:35 and 16:35 it is ok, but when i do 20:30 to 01:30, it gives me like 18 hours interval.. anyone have an idea? NSString *startDate= starthere.text; NSString *endDate = endhere.text; NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; [dateFormatter setDateFormat:@"HH:mm"]; NSDate *dateSelected = [dateFormatter dateFromString:startDate]; NSDate *dateSelected2 = [dateFormatter dateFromString:endDate]; [dateFormatter release]; interval = [dateSelected2 timeIntervalSinceDate:dateSelected];

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