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  • How do I maximize a function in Mathematica which takes in a variable length list as input?

    - by Mike
    I have a time-series like function which gives an output based on a list of real numbers(i.e. you can run the function on a list of 1,2,3,... real numbers). The issue I'm encountering is how to maximize the function for a given list length(subject to a set of constraints). I could fix the function to a fixed number of real numbers(i.e. f [x_Real, y_Real] instead of f[x_List]) and treat x and y as the first two elements of the list, and call Maximize on the function, but this is not really elegant. I want to be able to easily change the number of elements in the list. What is the best way to optimize a function like I described, which takes a list as an argument, for a fixed list length?

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  • How to use > in an xargs command?

    - by jesse
    I want to find a bash command that will let me grep every file in a directory and write the output of that grep to a separate file. My guess would have been to do something like this ls -1 | xargs -I{} "grep ABC '{}' > '{}'.out" but, as far as I know, xargs doesn't like the double-quotes. If I remove the double-quotes, however, then the command redirects the output of the entire command to a single file called '{}'.out instead of to a series of individual files. Does anyone know of a way to do this using xargs? I just used this grep scenario as an example to illustrate my problem with xargs so any solutions that don't use xargs aren't as applicable for me.

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  • Javascriptlibrary more efficient than Rickshaw for realtime visualizations

    - by dan kutz
    I want to visualize data as time-series graphs on mobile devices(tablets) and therefore stumbled upon rickshaw, which is based on D3. First I must say I was a little bit confused when I realized that realtime in web design is defined totally different to realtime in engineering which has fixed(and often very short) timeframes. Anyway my aim is to visualize the data as fast as possible, and on older tablets visualization with rickshaw is quite slow. Can anybody recommend another library, which may be more efficient in rendering? Or is there no way out and I have to go native? regards Dan.

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  • matrix image processing in OpenGL CE

    - by iHorse
    im trying to create an image filter in OpenGL CE. currently I am trying to create a series of 4x4 matrices and multiply them together. then use glColorMask and glColor4f to adjust the image accordingly. I've been able to integrate hue rotation, saturation, and brightness. but i am having trouble adding contrast. thus far google hasn't been to helpful. I've found a few matrices but they don't seem to work. do you guys have any ideas?

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  • Unwanted virtual keyboard in Blackberry app

    - by matkas
    I have developed a Blackberry app for the 4.5 os series. It works fine on all device except on the storm 1 (storm2 untested). The problem (on the storm) is that the main screen of my application (and all other screens in fact) is shown with the virtual keybord. But there is no text field displayed on the screen that would justify the VK to show up. I have bitmap fields and button fields only on that screen. The use of a single program for all devices (4.5 and up) is seriously preferred. What is causing the VK to show up and what can I do to prevent it (in JDE 4.5)?

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  • UIScrollView carousel menu

    - by user303753
    Hi all, I'm trying to figure out if I can get what I want out of UIScrollView through some trickery or whether I need to roll my own scroll view I have a series of items in row that I want to scroll through. One item should always be centered in the view, but other items should be visible to either side. In other words, I want normal scrolling and edge bouncing, but I want the deceleration when the user ends a touch to naturally settle at some specified stop point. (Actually now that I think of it, this behavior is similar to coverflow in this respect.)

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  • K&R Exercise 1-21 - Mental incomprehension.

    - by asdfg
    The "impossible" K&R exercise. "Write a program entab that replaces strings of blanks by the minimum number of tabs and blanks to achieve the same spacing. Use the same tab stops, say every n columns. Should n be a variable or a symbolic parameter?" The problem I'm having is, I'm unsure about how to even do this correctly. I know it's not very explanatory, but that's pretty much the problem here. Most of the examples I've seen have counted a number of blanks, and replaced those series with a tab, but this isn't what its asking, I reckon I understand what its asking, but currently feel unable to do this. Could anyone help :)

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  • What's a better choice for SQL-backed number crunching - Ruby 1.9, Python 2, Python 3, or PHP 5.3?

    - by Ivan
    Crterias of 'better': fast im math and simple (little of fields, many records) db transactions, convenient to develop/read/extend, flexible, connectible. The task is to use a common web development scripting language to process and calculate long time series and multidimensional surfaces (mostly selectint/inserting sets of floats and dong maths with rhem). The choice is Ruby 1.9, Python 2, Python 3, PHP 5.3, Perl 5.12, JavaScript (node.js). All the data is to be stored in a relational database (due to its heavily multidimensional nature), all the communication with outer world is to be done by means of web services.

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  • Math Looping Between Min and Max Using Mod?

    - by TheDarkIn1978
    i'm attempting to build a tiny (or perhaps not so tiny) formula that will contain numbers between a set min and max, but also loop these numbers so they are not clipped if they are outside of the range. so far, this is what i have. min1 = 10 max1 = 90 val1 = 92 //will make 12, which is what i want since it loops formula: min(max(min1,min(val1,max1)),mod(val1,max1)+min1) however, i'd like it to loop the other direction also, so that if val1 is 5, which is -5 outside of min1, it will become 85. another problem i'm running into is that max1 % max1 != max1 as i want it to, since the max is part of the range trying to be clear, here are some examples of desired output based on a range with looping min1 = 10 max1 = 90 ---------------------------------------------- val1 = 30 //within range: stays as 30 val1 = 90 //within range: stays as 90 val1 = -6 //below range: loops to becomes 84 val1 = 98 //above range: loops to becomes 18 i'd like not to resort to using a series of if/else statements, but one would be fine if it's absolutely required. is that even possible?

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  • Possible to capture the returned value from a Python list comprehension for use a condition?

    - by Joe
    I want to construct a value in a list comprehension, but also filter on that value. For example: [expensive_function(x) for x in generator where expensive_function(x) < 5] I want to avoid calling expensive_function twice per iteration. The generator may return an infinite series, and list comprehensions aren't lazily evaluated. So this wouldn't work: [y in [expensive_function(x) for x in generator where expensive_function(x)] where y < 5] I could write this another way, but it feels right for a list comprehension and I'm sure this is a common usage pattern (possible or not!).

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  • Advice about a good Java book?

    - by camac1
    Hi people, I am new to Java but have experience programming in C/C++/C#. I wanted to learn Java SE 6 first before moving to Java EE 6. After making some research online for appropriate Java SE 6 books, I found that these are appropriate for me to get an excellent idea of Java SE 6: 1) Head First Java, 2nd Edition 2) An Intermediate Level Book <----------- 3) Effective Java (2nd Edition) 4) Java Concurrency in Practice 5) Java Generics and Collections 6) Java Concise Reference Series: Swing And AWT 7) Java Reflection in Action However, I am having trouble choosing an Intermediate Level Book which will provide me with breadth and depth in Java SE 6. I was thinking about the book "Thinking in Java (4th Edition)"....Unfortunately, its deals with Java SE 5 and not the latest version. Could anybody please advice me an intermediate level book which could provide me with breadth and depth in Java SE 6. Regards

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  • Setting asp:Image URL using Javascript function

    - by Anil
    Hi all I have a series of asp:ImageButtons and one asp:Image(Big). Clicking on each ImageButton should change the ImageUrl of asp:Image to a new ImageUrl. How can we handle this using one Javascript function. Because I dont wanna code ImageButton_Click for each and every asp:ImageButton. This makes my application run very slow and also pass too many server requests. Any ideas ????How to design one powerful Javascript function. By the way when the user clicks on ImageButton...the ImageUrl that has to be set to asp:Image(Big) is same as that of ImageButton. This might help a bit. Thanks in advance

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  • How to optimize an SQL query with many thousands of WHERE clauses

    - by bugaboo
    I have a series of queries against a very mega large database, and I have hundreds-of-thousands of ORs in WHERE clauses. What is the best and easiest way to optimize such SQL queries? I found some articles about creating temporary tables and using joins, but I am unsure. I'm new to serious SQL, and have been cutting and pasting results from one into the next. SELECT doc_id, language, author, title FROM doc_text WHERE language='fr' OR language='es' SELECT doc_id, ref_id FROM doc_ref WHERE doc_id=1234567 OR doc_id=1234570 OR doc_id=1234572 OR doc_id=1234596 OR OR OR ... SELECT ref_id, location_id FROM ref_master WHERE ref_id=098765 OR ref_id=987654 OR ref_id=876543 OR OR OR ... SELECT location_id, location_display_name FROM location SELECT doc_id, index_code, FROM doc_index WHERE doc_id=1234567 OR doc_id=1234570 OR doc_id=1234572 OR doc_id=1234596 OR OR OR x100,000 These unoptimized query can take over 24 hours each. Cheers.

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  • Add version control to existing SQL Server database

    - by ederbf
    I am part of a development team currently working with a database that does not have any kind of source control. We work with SQL Server 2008 R2 and have always managed the DB directly with SSMS. It now has ~340 tables and ~1600 stored procedures, plus a few triggers and views, so it is not a small DB. My goal is to have the DB under version control, so I have been reading articles, like Scott Allen's series (http://bitly.com/9cJmGR) and many old SO related questions. But I am still unable to decide on how to proceed. What I'm thinking of is to script the database schema in one file, then procedures, triggers and views in one file each. Then keep everything versioned under Mercurial. But of course, every member of the team can access SSMS and directly change the schema and procedures, with the possibility that any of us can forget to replicate those changes in the versioned files. What better options are there? And, did I forget any element worth having source control of?

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  • Last Observation Carried Forward In a data frame?

    - by Tal Galili
    Hi all, I wish to implement a "Last Observation Carried Forward" for a data set I am working on which has missing values at the end of it. Here is a simple code to do it (question after it): LOCF <- function(x) { # Last Observation Carried Forward (for a left to right series) LOCF <- max(which(!is.na(x))) # the location of the Last Observation to Carry Forward x[LOCF:length(x)] <- x[LOCF] return(x) } # example: LOCF(c(1,2,3,4,NA,NA)) LOCF(c(1,NA,3,4,NA,NA)) Now this works great for simple vectors. But if I where to try and use it on a data frame: a <- data.frame(rep("a",4), 1:4,1:4, c(1,NA,NA,NA)) a t(apply(a, 1, LOCF)) # will make a mess It will turn my data frame into a character matrix. Can you think of a way to do LOCF on a data.frame, without turning it into a matrix? (I could use loops and such to correct the mess, but would love for a more elegant solution) Cheers, Tal

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  • bytea type & nulls, Postgres

    - by Thanatos
    I'm using a bytea type in PostgreSQL, which, to my understanding, contains just a series of bytes. However, I can't get it to play well with nulls. For example: =# select length(E'aa\x00aa'::bytea); length -------- 2 (1 row) I was expecting 5. Also: =# select md5(E'aa\x00aa'::bytea); md5 ---------------------------------- 4124bc0a9335c27f086f24ba207a4912 (1 row) That's the MD5 of "aa", not "aa\x00aa". Clearly, I'm Doing It Wrong, but I don't know what I'm doing wrong. I'm also on an older version of Postgres (8.1.11) for reasons outside of my control. (I'll see if this behaves the same on the latest Postgres as soon as I get home...)

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  • Add a listener inside or outside get method

    - by James P.
    I'm learning Swing and have composed an interface using a series of get methods to add components. Is it a good practise to add a Listener inside a get method as follows? I'd like to make things as decoupled as possible. private JButton getConnectButton() { if (connectButton == null) { connectButton = new JButton(); connectButton.setText("Connect"); connectButton.setSize(new Dimension(81, 16)); connectButton.setLocation(new Point(410, 5)); connectButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { // actionPerformed code goes here } }); } return connectButton; }

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  • Naive question about implementing RSS

    - by interstar
    I have a naive question about RSS feeds. I have a series of timed events which appear on my site and that I make available as an RSS feed for other applications to import. Who is typically responsible for truncating this feed? Over the next year, I can see my feed having thousands of items. Should the URL mysite.com/rss always return all items? And leave it to the readers to just show the most recent? Or is it more customary that I only return, say, the top 50? Expecting the readers to cache older items? (And, if so, is there a convention for readers to ask the server for the "next page")? What is the typical behaviour of something like FriendFeed when it pulls in an RSS stream?

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  • changing a picker to table view OR having multiple table views on the same view

    - by Brodie4598
    Hello - My iPad app was rejected due to my use of a picker. The picker was used to control a table view. In my view, a picker was displaying a series of items and when one of those items was selected, it used that selection to populate a table with data. (hopefully that makes sense). Now I need to do this without the picker so I need to have the data that was in the picker be represented in a table view. My question, is how do I have multiple tableViews in the same view? I'm guessing I need to have some kind of if statement in the tableview delegate methods, but I'm not quite sure what the if statement needs to be. Or maybe i'm thinking of this the totally wrong way thanks

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  • Learning about version control systems, Git, SVN

    - by anijhaw
    I am a basic SVN user now trying to learn GIT for a new position. I am trying the usual reading docs and watching videos. However after doing all that I still feel that there is a lot that I do not know. I was wondering if there is a place like project Euler for programming languages, that provides a series of exercises that you can do just to increase your confidence and test your knowledge about a version control system. Something thats generic enough and gets you up to speed with how to do basic things. This could also serve as a comparison point of sorts between multiple VCSs, that would show what things are easy in which VCS. If there is nothing I was planning to document my journey in learning GIT and the create an exercise of this sort.

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  • Parse a json(?) string using php

    - by passatgt
    I have a string, more specifically, this one: a:16:{s:9:"pseudonym";O:16:"SimpleXMLElement":0:{}s:14:"parallel_title";O:16:"SimpleXMLElement":0:{}s:9:"title_var";O:16:"SimpleXMLElement":0:{}s:6:"series";O:16:"SimpleXMLElement":0:{}s:9:"vol_title";O:16:"SimpleXMLElement":0:{}s:9:"reference";O:16:"SimpleXMLElement":0:{}s:10:"bound_with";O:16:"SimpleXMLElement":0:{}s:15:"general_remarks";O:16:"SimpleXMLElement":0:{}s:6:"copies";O:16:"SimpleXMLElement":1:{i:0;s:1:"1";}s:11:"remarks_BPH";O:16:"SimpleXMLElement":0:{}s:3:"ICN";O:16:"SimpleXMLElement":1:{i:0;s:4:"neen";}s:10:"provenance";O:16:"SimpleXMLElement":0:{}s:7:"binding";O:16:"SimpleXMLElement":0:{}s:10:"size_hxwxd";O:16:"SimpleXMLElement":0:{}s:6:"BookID";O:16:"SimpleXMLElement":1:{i:0;s:4:"6271";}s:5:"repro";O:16:"SimpleXMLElement":0:{}} Is it possible to parse this string somehow? I need to display the keys and values in a list. I tried to use json_decode but it not returns anything, even with the second true parameter(json_decode($string,true))

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  • Vertical Lines appearing rapidly on HP DV-1211tu screen

    - by Vibin Jith
    My laptop (HP DV-1211tu series) is more than 1 year old but was working fine. Then about couple of months back, there appeared ONE vertical line on my screen and I was told that I might have to change the screen!! So I ignored it and continued to work on my laptop. In the past week though there have been more lines appearing and its about 9 on last count. I am assuming this is a display problem but what do I do???? I can't afford a new screen. Any help / suggestions would be greatly appreciated !!! Thanks.

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  • Can Atom be used for things besides syndication feeds?

    - by greim
    Purely in terms of its conceptual model, is the purpose of Atom (and RSS) only to provide a time-sequential series of frequently-updated items, such as "most recent blog posts" or "last twenty SVN commits," or can Atom be legitimately used to represent static and/or non-time-sequential listings/indices? As an example, "index of files under this directory", "dog breeds" or "music genres". Even if there's a date associated with the items, like a file's last modified date, what if you don't necessarily want time to be the primary consideration when you represent that model to your users? The context for this is passing around (generating and consuming) lists of things in a REST-ful environment, hopefully using a well-understood format, where "date something was created/updated" is a pertinent detail, but not the primary consideration. I realize there's probably no right answer, but wanted to get some perspectives. Thanks.

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  • Java Application/Thread Server

    - by Manrico Corazzi
    I am looking for something very close to an application server with these features: it should handle a series of threads/daemons, allowing the user to start-stop-reload each one without affecting the others it should keep libraries separated between different threads/daemons it should allow to share some libraries Currently we have some legacy code reinventing the wheel... and not a perflectly round-shaped one at that! I thought to use Tomcat, but I don't need a web server, except maybe for the simple backoffice user interface (/manager/html). Any suggestion? Is there a non-web application server, or is there a better alternative to Tomcat (more lightweight, for example, or easier to configure)? Thanks in advance.

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  • data path (travel) of tcp data from "write" syscall downto I/O registers programming

    - by osgx
    Hello Is there a good overview of tcp data path in Linux (2.6, not 2.4 if the path actually differ)? Where is a packet on different stages of tcp/ip stack handling? How packet is packed to tcp segment, then ip packet. How it is transmitted to network card? (with series of I/O regs write and DMA?) Is it transmitted to network card in the "write" syscall handler (with some deep callstack) or is it transmitted at some other moment?

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