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Search found 125 results on 5 pages for 'rusty'.

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• PROLOG all different

  - by inspectorG4dget

  Hello SO, I have a very weird problem with PROLOG. I have used it before, but it's been a while and I'm rusty. I have a list of variables and I need to ensure that none of them are the same. I have tried: use_module(library(bounds)). all_different(A, B, C, D, 6, 8). However, when I try this, I get an error saying that all_different/6 is undefined. How can I go about solving this issue? Is there any library function that I can call directly for this? I am VERY stuck and would greatly appreciate any help. Thanks in advance.

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• Correct permutation cycle for Verhoeff algorithm

  - by James

  Hello, I'm implementing the Verhoeff algorithm for a check digit scheme, but there seems to be some disagreement in web sources as to which permutation cycle should form the basis of the permutation table. Wikipedia uses: (36)(01589427) while apparently, Numerical Recipies uses a different cycle and this book uses: (0)(14)(23)(56789), quoted from a 1990 article by Winters. It also notes that Verhoeff used the one Wikipedia quotes. Now, my number theory is a little rusty, but the Wikipedia cycle clearly will repeat after the 8th power, while the book one will take 10, despite it saying that s^8=s. Table 2.14(b) has other errors in the 2-cycles, so this is dubious anyway. Unfortunately, I don't have copies of the original articles (and am too tight to pay/disgusted that 40-year old knowledge is still being held to ransom by publishers), nor a copy of Numerical Recipes to check (and am loath to install their paranoia-induced copy protection plug-in to view online). So does any one know which is correct? Are they both correct?

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• Should Java IOException have been an unchecked RuntimeException?

  - by Derek Mahar

  Do you agree that the designers of Java class java.io.IOException should have made it an unchecked run-time exception derived from java.lang.RuntimeException instead of a checked exception derived only from java.lang.Exception? I think that class IOException should have been an unchecked exception because there is little that an application can do to resolve problems like file system errors. However, in When You Can't Throw An Exception, Elliotte Rusty Harold claims that most I/O errors are transient and so you can retry an I/O operation several times before giving up: For instance, an IOComparator might not take an I/O error lying down, but — because many I/O problems are transient — you can retry a few times, as shown in Listing 7: Is this generally the case? Can a Java application correct I/O errors or wait for the system to recover? If so, then it is reasonable for IOException to be checked, but if it is not the case, then IOException should be unchecked so that business logic can delegate handling this exception to a separate system error handler.

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• Getting ID of an instance newly launched with ec2-api-tools

  - by Jonik

  I'm launching an EC2 instance, by invoking ec2-run-instances from simple a bash script, and want to perform further operations on that instance (e.g. associate elastic IP), for which I need the instance id. The command is something like ec2-run-instances ami-dd8ea5a9 -K pk.pem -C cert.pem --region eu-west-1 -t c1.medium -n 1, and its output: RESERVATION r-b6ea58c1 696664755663 default INSTANCE i-945af9e3 ami-dd8ea5b9 pending 0 c1.medium 2010-04-15T10:47:56+0000 eu-west-1a aki-b02a01c4 ari-39c2e94d In this example, i-945af9e3 is the id I'm after. So, I'd need a simple way to parse the id from what the command returns - how would you go about doing it? My AWK is a little rusty... Feel free to use any tool available on a typical Linux box. (If there's a way to get it directly using EC2-API-tools, all the better. But afaik there's no EC2 command to e.g. return the id of the most recently launched instance.)

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• Video Synthesis - Making waves, pattern, gradients...

  - by Nathan

  I'm writing a program to generate some trippy visuals. My code paints each pixel with a random blue value which loops at 0.04 second intervals. for (y = 0; y < 5.5; y += 0.2) { for (x = 0; x < 7.5; x += 0.2) { b = rand() / ((double) RAND_MAX); setPixelColor(x,y,r,g,b); } } I'd like to do more than just make blue noise... but my maths is a bit rusty, and Google isn't helping me much today, so it would be great if you could share anything you know about making waves, patterns, gradient animations, etc or links to such material.

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• Java == operator. "Invalid assignment operator"

  - by Tom

  Hi, I was trying to write a simple method boolean validate(MyObject o) { return o.getPropertyA() == null && o.getPropertyB()==null; } And got a strange error on the == null part. Maybe my Java is rusty after a season in PLSQL. Consider this: Integer i = 4; i ==null; //compile error: Syntax error on token ==. Invalid assignment operator. Integer i2 = 4; if (i==null); //No problem How can this be ? Any explanation ? Im using jdk160_05.

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• How can something like BOSH be implemented using Java Servlets

  - by John

  BOSH (Bidirectional-streams Over Synchronous HTTP) is a sneaky way of implementing 2-way client-server communication in situations where true server-push is not allowed, most obviously to let a server push data to a browser client without having to use client polling. It works by the client sending a request to the server, and the server doesn't respond immediately... rather it remembers the request but only responds when it has some data to send. When this happens the client immediately sends another request so there is virtually always a 'stored request' sitting on the server ready to push data to the client. At least, that's how I think it works! My question is how you can do this using a Java EE stack i.e standard servlets. I'm rusty with them, is it allowed to send no response and cache the request somehow? If anyone could share (pseudo) code what a servlet class for handling BOSH might look like, I'd be real grateful.

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• MySql UDF using shared library won't load

  - by Jarrod

  I am attempting to create a mysql UDF which will match a fingerprint using Digital Persona's free linux SDK library. I have written a trivial UDF as a learning experience which worked fine. However, when I added a dependency to Digital Persona's shared object I can no longer get MySql to load my UDF. I added includes to DP's headers and compiled my UDF using: gcc -fPIC -Wall -I/usr/src/mysql-5.0.45-linux-i686-icc-glibc23/include -shared -o dp_udf.so dp_udf.cc I also tried adding the -static argument, but whenever I restart MySql, I get the error: Can't open shared library 'dp_udf.so' (errno: 0 /usr/local/mysql/lib/plugin/dp_udf.so: undefined symbol: MC_verifyFeaturesEx) MC_verifyFeaturesEx is a function defined "dpMatch.h" which I included, and is implemented in libdpfpapi.so which I have tried placing in the same location as my dp_udf.so and in /usr/lib. Am I doing something wrong with my call to gcc (my C++ skills are rusty) or does MySql not allow UDFs to use additional shared objects?

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• GA written in Java

  - by EnderMB

  I am attempting to write a Genetic Algorithm based on techniques I had picked up from the book "AI Techniques for Game Programmers" that uses a binary encoding and fitness proportionate selection (also known as roulette wheel selection) on the genes of the population that are randomly generated within the program in a two-dimensional array. I recently came across a piece of pseudocode and have tried to implement it, but have come across some problems with the specifics of what I need to be doing. I've checked a number of books and some open-source code and am still struggling to progress. I understand that I have to get the sum of the total fitness of the population, pick a random number between the sum and zero, then if the number is greater than the parents to overwrite it, but I am struggling with the implementation of these ideas. Any help in the implementation of these ideas would be very much appreciated as my Java is rusty.

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• Shortest distance between a point and a line segment

  - by Eli Courtwright

  I need a basic function to find the shortest distance between a point and a line segment. Feel free to write the solution in any language you want; I can translate it into what I'm using (Javascript). EDIT: My line segment is defined by two endpoints. So my line segment AB is defined by the two points A (x1,y1) and B (x2,y2). I'm trying to find the distance between this line segment and a point C (x3,y3). My geometry skills are rusty, so the examples I've seen are confusing, I'm sorry to admit.

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• Did your masters degree help you as a programmer?

  - by Tim Sally

  There is a previous question ("Is a masters degree overkill?"), which is about the types of jobs available and the value of a masters when trying to get a job. What I am curious about the impact of programming ability. I know you usually write a masters thesis on some topic, which I imagine forces you to specialize. Do your programming skills actually get rusty while getting a masters, or is there some benefit? Would it be more beneficial to work for the two years instead?

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• Should class IOException in Java have been an unchecked RuntimeException?

  - by Derek Mahar

  Do you agree that the designers of Java class java.io.IOException should have made it an unchecked run-time exception derived from java.lang.RuntimeException instead of a checked exception derived only from java.lang.Exception? I think that class IOException should have been an unchecked exception because there is little that an application can do to resolve problems like file system errors. However, in When You Can't Throw An Exception, Elliotte Rusty Harold claims that most I/O errors are transient and so you can retry an I/O operation several times before giving up: For instance, an IOComparator might not take an I/O error lying down, but — because many I/O problems are transient — you can retry a few times, as shown in Listing 7: Is this generally the case? Can a Java application correct I/O errors or wait for the system to recover? If so, then it is reasonable for IOException to be checked, but if it is not the case, then IOException should be unchecked so that business logic can delegate handling of this exception to a separate system error handler.

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• Batch file search and replace using wildcards?

  - by user329358

  Batch file search and replace using wildcards I have a html (txt) file I am using as a template or sourcefile to create further html files.  Filename = pg_0001.htm and it contains a line of code thus: pg_0001.jpg I want to parse the pg_0001.htm sourcefile, increment and replace the jpeg string, like this:  "pg_0002.jpg", and then output the edited htm file to a new filename pg_0002.htm I then take each newly created file (pg_0002.htm, pg_0003.htm etc) as the sourcefile and repeat the processing until I have reached my target goal (let's say 100 newly created htm files containing code to display the corresponding jpeg. It must be done this way (fileX.htm containing fileX.jpg) because there is other javascript that uses these incremented filenames as function input. I used to know how to write incrementing batch files many years ago but I'm old & very rusty now.  Can anyone please help me do this?  Many thanks in advance. regards Harry

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• finding an adjacent node in xml through xpath

  - by kolosy

  i have a deeply nested structure (actually parsing out xhtml, so lots of nasty), like so: <tr> <td> <font id="blah"> stuff </font> </td> </tr> <tr> <td> more stuff </td> </tr> and this repeats in a long table. i need an xpath expression that will select the second font tag (or rather it's text()). i was looking at the preceding-sibling axis, but something isn't quite working right. something along the lines of (and pardon me if this is ridiculous, my xpath is rusty) //tr[preceding-sibling::tr/td/font/b]/td/text()

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• iPhone App Development - mathematical sysmbols

  - by mcglynnconsultancy

  I am quite the beginner - but I have a lot of experience with respect to Electrical Engineering and formulas - over 30 years worth! Trying to construct an app for the iPhone. Loaded the SDK, bought myself a Mac, got a couple of "Chapter" pages written by John at Alpha Aviation - who recomended I try this site. How do I - well for example I enetered 400/1.732 - it came out like it was a web address with an underline! How can I get mathematical symbols like - sqare root, to the power of, subscript, superscript. I'd like to insert a few "calculator" pages but don't know how to. Appreciate I have only been doing this for the last week or so - so I am still quite rusty compared to what I wrote many years ago. Can anyone help? cheers

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• Finding all instances of a substring in a string

  - by Mr Aleph

  In my last question I asked about parsing the links out of an HTML page. Since I haven't found a solution yet I thought I tried something else in the meantime: search for every <a href= and copy whatever is there until I hit a </a>. Now, my C is a bit rusty but I do remember i can use strstr() to get the first instance of that string, but how do I get the rest? Any help is appreciated. PS: No. This is not homework on school or something like that. Just so you know.

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• Shortest distance between a point and a line segment

  - by Eli Courtwright

  I need a basic function to find the shortest distance between a point and a line segment. Feel free to write the solution in any language you want; I can translate it into what I'm using (Javascript). EDIT: My line segment is defined by two endpoints. So my line segment AB is defined by the two points A (x1,y1) and B (x2,y2). I'm trying to find the distance between this line segment and a point C (x3,y3). My geometry skills are rusty, so the examples I've seen are confusing, I'm sorry to admit.

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• Can Somebody Explain this java code

  - by dubbeat

  Hi, I'm just starting out on android and my java is verry rusty. I can't remember ever seeing a function nested in another function like this before. Could somebody explain to me exactly what final does and explain why you would nest a function in another like this? private final Handler handler = new Handler() { @Override public void handleMessage(final Message msg) { Log.v(Constants.LOGTAG, " " + ReviewList.CLASSTAG + " worker thread done, setup ReviewAdapter"); progressDialog.dismiss(); if ((reviews == null) || (reviews.size() == 0)) { empty.setText("No Data"); } else { reviewAdapter = new ReviewAdapter(ReviewList.this, reviews); setListAdapter(reviewAdapter); } } };

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• What should I do to practice?

  - by simion

  I start a year long industrial placement in September where i will be coding in Java predominantly. I am going to use the summer to brush up on my Java as in year one of the degree Java was the main language taught for OOP modules. However this year i have had no Java exposure except for an algorithms module, which was one of eight, so as you can see i am probably getting really rusty!. What i wanted to know is, how does the "real world" java programming differ from university coding and what do you suggest i brush up on that would be different to my normal workings. As a start I definitely need to get familiar with a professional IDE like NetBeans, opposed to having used BlueJ throughout but more specifically what coding practices should I get more familiar with. I appreciate they wont expect me to be a qualified full developer and will give me time, but I would like to hit the ground running as it were, with me having full hopes to secure a permanent position after I finish my degree.

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• PhysX: Joint friction/"stiff" joints

  - by SigTerm

  I'm working with physx (trying to add ik to ragdoll) at the moment. For some reason, all ragdoll joints are frictionless, and as a result, ragdoll tend to "wobble", especially when it is hung in the air and is connected to several moving kinematic actors. I would like to add friction to the joints and make them "stiff". Imagine a door (with extremely rusty hinge) that needs to be kicked several times to be open - i.e. it rotates around the hinge, but not much, quickly stops, and large force is required to make it rotate. Or think about art manikins (see google images for pictures) - their limbs move around, but they do not swing around freely. Unfortunately, I can't find anything related to joint friction in physx. I've checked documentation, google, and headers, and couldn't find anything useful. So, how do I implement stiff joints/joint friction with physx? (I think) I've seen physx games without that problem, so apparently there should be some way to do that.

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• What should i do to practise?

  - by simion

  Hi guys I start a year long industrial placement in september where i will be coding in java predominantly. I am going to use the summer to brush up on my java as in year one of the degree java was the main language taught for OOP modules. However this year i have had no java exposure except for an algorithms module, which was one of eight, so as you can see i am probably getting really rusty!. What i wanted to know is, how does the "real world" java programming differ from university coding and what do you suggest i brush up on that would be different to my normal workings. As a start i definatley need to get familiar with a professional IDE like netbeans, opoosed to havign used BlueJ throughout but more specifically what coding practises should i get more familiar with I appreciate they wont expect me to be a qualified full developer and will give me time, but i would like to hit the ground running as it were, with me having full hopes to secure a perminant position after i finish my degree. Thanks for reading

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• Shortest distance between two line segments

  - by Frank

  I need a function to find the shortest distance between two line segments. A line segment is defined by two endpoints. So for example one of my line segments (AB) would be defined by the two points A (x1,y1) and B (x2,y2) and the other (CD) would be defined by the two points C (x1,y1) and D (x2,y2). Feel free to write the solution in any language you want and I can translate it into javascript. Please keep in mind my geometry skills are pretty rusty. I have already seen http://stochastix.wordpress.com/2008/12/28/distance-between-two-lines/ and I am not sure how to translate this into a function. Thank you so much for help.

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• C#: split a string into runs of characters, numbers and delimited strings and process it

  - by nrkn

  OK my regex is a bit rusty and I've been struggling with this particular problem... I need to split and process a string containing any number of the following, in any order: Chars (lowercase letters only) Quote delimited strings Ints The strings are pretty weird (I don't have control over them). When there's more than one number in a row in the string they're seperated by a comma. They need to be processed in the same order that they appeared in the original string. For example, a string might look like: abc20a"Hi""OK"100,20b With this particular string the resulting call stack would look a bit like: ProcessLetters( new[] { 'a', 'b', 'c' } ); ProcessInts( 20 ); ProcessLetters( 'a' ); ProcessStrings( new[] { "Hi", "OK" } ); ProcessInts( new[] { 100, 20 } ); ProcessLetters( 'b' ); What I could do is treat it a bit like CSV, where you build tokens by processing the characters one at a time, but I think it could be more easily done with a regex?

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• I'd want a method to be called only by objects of a specific class

  - by mp

  Suppose you have this class: public class A { private int number; public setNumber(int n){ number = n; } } I'd like the method setNumber could be called only by objects of a specific class. Does it make sense? I know it is not possible, is it? Which are the design alternatives? Some well known design pattern? Sorry for the silly question, but I'm a bit rusty in OO design.

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• Javascript Pointers question with Dates

  - by Mega Matt

  I noticed this situation in my code (unfortunately), and was able to duplicate it in my own JS file. So I have this code: var date1 = new Date(); // today var date2 = date1; date2 = date2.setDate(date2.getDate() + 1); // what is date1? After this code executes, date1 is today's date + 1! This harkens back to my undergrad days when I learned about pointers, and I guess I'm a little rusty. Is that what's happening here? Obviously I've moved the assignment away from date1, and am only modifying date2, but date1 is being changed. Why is this the case? Incidentally, after this code executes date2 is a long number like 1272123603911. I assume this is the number of seconds in the date, but shouldn't date2 still be a Date object? setDate() should return a Date object... Thanks for the help.

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