Search Results

Search found 7216 results on 289 pages for 'low cost'.

Page 245/289 | < Previous Page | 241 242 243 244 245 246 247 248 249 250 251 252  | Next Page >

• When optimizing database queries, what exactly is the relationship between number of queries and siz

  - by williamjones

  To optimize application speed, everyone always advises to minimize the number of queries an application makes to the database, consolidating them into fewer queries that retrieve more wherever possible. However, this also always comes with the caution that data transferred is still data transferred, and just because you are making fewer queries doesn't make the data transferred free. I'm in a situation where I can over-include on the query in order to cut down the number of queries, and simply remove the unwanted data in the application code. Is there any type of a rule of thumb on how much of a cost there is to each query, to know when to optimize number of queries versus size of queries? I've tried to Google for objective performance analysis data, but surprisingly haven't been able to find anything like that. Clearly this relationship will change for factors such as when the database grows in size, making this somewhat individualized, but surely this is not so individualized that a broad sense of the landscape can't be drawn out? I'm looking for general answers, but for what it's worth, I'm running an application on Heroku.com, which means Ruby on Rails with a Postgres database.

  Read the article

• Caching sitemaps in django

  - by michuk

  I implemented a simple sitemap class using django's default sitemap app. As it was taking a long time to execute, I added manual caching: class ShortReviewsSitemap(Sitemap): changefreq = "hourly" priority = 0.7 def items(self): # try to retrieve from cache result = get_cache(CACHE_SITEMAP_SHORT_REVIEWS, "sitemap_short_reviews") if result!=None: return result result = ShortReview.objects.all().order_by("-created_at") # store in cache set_cache(CACHE_SITEMAP_SHORT_REVIEWS, "sitemap_short_reviews", result) return result def lastmod(self, obj): return obj.updated_at The problem is that memcache allows only max 1MB object. This one was bigger that 1MB, so storing into cache failed: >7 SERVER_ERROR object too large for cache The problem is that django has an automated way of deciding when it should divide the sitemap file into smalled ones. According to the docs (http://docs.djangoproject.com/en/dev/ref/contrib/sitemaps/): You should create an index file if one of your sitemaps has more than 50,000 URLs. In this case, Django will automatically paginate the sitemap, and the index will reflect that. What do you think would be the best way to enable caching sitemaps? - Hacking into django sitemaps framework to restrict a single sitemap size to, let's say, 10,000 records seems like the best idea. Why was 50,000 chosen in the first place? Google advice? random number? - Or maybe there is a way to allow memcached store bigger files? - Or perhaps onces saved, the sitemaps should be made available as static files? This would mean that instead of caching with memcached I'd have to manually store the results in the filesystem and retrieve them from there next time when the sitemap is requested (perhaps cleaning the directory daily in a cron job). All those seem very low level and I'm wondering if an obvious solution exists...

  Read the article

• Query on object id in VQL

  - by Banang

  I'm currently working with the versant object database (using jvi), and have a case where I need to query the database based on an object id. What I'm trying to achieve is something along the lines of Employee employee = new Employee("Mr. Pickles"); session.commit(); FundVQLQuery q = new FundVQLQuery(session, "select * from Employee employee where employee = $1"); q.bind(employee); q.execute(); However, I'm finding out the hard way (I get an EVJ_NOT_A_VALID_KEY_TYPE error thrown at me) that this is infact not the way to do it. Anyone got any experience in working with VQL? Your help is much apreciated! A small clarification: The problem is I'm running some performance tests on the database using the pole position framework, and one of the tests in that framework requires me to fetch an object from the database using either an object reference or a low level object id. Thus, I'm not allowed to reference specific fields in the employee object, but must perform the query on the object in its entirety. So, it's not allowed for me to go "select * from Employee e where e.id = 4", I need it to use the entire object. Accepted answer: Since there is some sort of lunacy magic built into SO that prevents me to mark an accepted answer after a bounty has run out, readers should know that the answer posted by Chris Holmes solves this issue. Readers are encouraged to up-vote his post to further signalize the correctness of his answer to any future readers of this thread.

  Read the article

• "Scheduling restart of crashed service", but no call to onStart() follows

  - by kostmo

  In the 1.6 API, is there a way to ensure that the onStart() method of a Service is called after the service is killed due to memory pressure? From the logs, it seems that the "process" that the service belongs to is restarted, but the service itself is not. I have placed a Log.d() call in the onStart() method, and this is not reached. To test my service under memory pressure, I spawn it from an activity, then launch the web browser and visit some Javascript-heavy websites like Slashdot until my service is killed. The logcat reads: 03-07 16:44:13.778: INFO/ActivityManager(52): Process com.kostmo.charbuilder.full (pid 2909) has died. 03-07 16:44:13.778: WARN/ActivityManager(52): Scheduling restart of crashed service com.kostmo.charbuilder.full/com.kostmo.charbuilder.DownloadImagesService in 5000ms 03-07 16:44:13.778: INFO/ActivityManager(52): Low Memory: No more background processes. 03-07 16:44:13.778: ERROR/ActivityThread(52): Failed to find provider info for android.server.checkin 03-07 16:44:13.778: WARN/Checkin(52): Can't log event SYSTEM_SERVICE_LOOPING: java.lang.IllegalArgumentException: Unknown URL content://android.server.checkin/events 03-07 16:44:18.908: INFO/ActivityManager(52): Start proc com.kostmo.charbuilder.full for service com.kostmo.charbuilder.full/com.kostmo.charbuilder.DownloadImagesService: pid=3560 uid=10027 gids={3003, 1015} 03-07 16:44:19.868: DEBUG/ddm-heap(3560): Got feature list request 03-07 16:44:20.128: INFO/ActivityThread(3560): Publishing provider com.kostmo.charbuilder.full.provider.character: com.kostmo.charbuilder.provider.ImageFileContentProvider

  Read the article

• [Java] Cluster Shared Cache

  - by GuiSim

  Hi everyone. I am searching for a java framework that would allow me to share a cache between multiple JVMs. What I would need is something like Hazelcast but without the "distributed" part. I want to be able to add an item in the cache and have it automatically synced to the other "group member" cache. If possible, I'd like the cache to be sync'd via a reliable multicast (or something similar). I've looked at Shoal but sadly the "Distributed State Cache" seems like an insufficient implementation for my needs. I've looked at JBoss Cache but it seems a little overkill for what I need to do. I've looked at JGroups, which seems to be the most promising tool for what I need to do. Does anyone have experiences with JGroups ? Preferably if it was used as a shared cache ? Any other suggestions ? Thanks ! EDIT : We're starting tests to help us decide between Hazelcast and Infinispan, I'll accept an answer soon. EDIT : Due to a sudden requirements changes, we don't need a distributed map anymore. We'll be using JGroups for a low level signaling framework. Thanks everyone for you help.

  Read the article

• iPhone - Memory Management - Using Leaks tool and getting some bizarre readings.

  - by Robert

  Hey all, putting the finishing touches on a project of mine so I figured I would run through it and see if and where I had any memory leaks. Found and fixed most of them but there are a couple of things regarding the memory leaks and object alloc that I am confused about. 1) There are 2 memory leaks that do not show me as responsible. There are 8 leaks attributed to AudioToolbox with the function being RegisterEmbeddedAudioCodecs(). This accounts for about 1.5 kb of leaks. The other one is detected immediately when the app begins. Core Graphics is responsible with the extra info being open_handle_to_dylib_path. For the audio leak I have looked over my audio code and to me it seems ok. self.musicPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:songFilePath] error:NULL]; [musicPlayer prepareToPlay]; [musicPlayer play] is called later on in a function. 2) Is it normal for there to be a spike in Object Allocation whenever a new view or controller is presented? My total memory usage is very, very low except for whenever I present a view controller. It spikes then immediately goes back down. I am guessing that this is just the phone handling all the information for switching or something. Blegh. Wall of text. Thanks in advance to anyone who helps! =)

  Read the article

• Help needed in grokking password hashes and salts

  - by javafueled

  I've read a number of SO questions on this topic, but grokking the applied practice of storing a salted hash of a password eludes me. Let's start with some ground rules: a password, "foobar12" (we are not discussing the strength of the password). a language, Java 1.6 for this discussion a database, postgreSQL, MySQL, SQL Server, Oracle Several options are available to storing the password, but I want to think about one (1): Store the password hashed with random salt in the DB, one column Found on SO and elsewhere is the automatic fail of plaintext, MD5/SHA1, and dual-columns. The latter have pros and cons MD5/SHA1 is simple. MessageDigest in Java provides MD5, SHA1 (through SHA512 in modern implementations, certainly 1.6). Additionally, most RDBMSs listed provide methods for MD5 encryption functions on inserts, updates, etc. The problems become evident once one groks "rainbow tables" and MD5 collisions (and I've grokked these concepts). Dual-column solutions rest on the idea that the salt does not need to be secret (grok it). However, a second column introduces a complexity that might not be a luxury if you have a legacy system with one (1) column for the password and the cost of updating the table and the code could be too high. But it is storing the password hashed with a random salt in single DB column that I need to understand better, with practical application. I like this solution for a couple of reasons: a salt is expected and considers legacy boundaries. Here's where I get lost: if the salt is random and hashed with the password, how can the system ever match the password? I have theory on this, and as I type I might be grokking the concept: Given a random salt of 128 bytes and a password of 8 bytes ('foobar12'), it could be programmatically possible to remove the part of the hash that was the salt, by hashing a random 128 byte salt and getting the substring of the original hash that is the hashed password. Then re hashing to match using the hash algorithm...??? So... any takers on helping. :) Am I close?

  Read the article

• ASP.NET MVC View ReRenders Part of Itself

  - by Jason

  In all my years of .NET programming I have not run across a bug as weird as this one. I discovered the problem because some elements on the page were getting double-bound by jQuery. After some (ridiculous) debugging, I finally discovered that once the view is completely done rendering itself and all its children partial views, it goes back to an arbitrary yet consistent location and re-renders itself. I have been pulling my hair out about this for two days now and I simply cannot get it to render itself only once! For lack of any better debugging idea, I've painstakingly added logging tracers throughout the HTML just so I can pin down what may be causing this. For instance, this code ($log just logs to the console): ... <script type="text/javascript">var x = 0; $log('1');</script> <div id="new-ad-form"> <script type="text/javascript">x++;$log('1.5', x);</script> ... will yield ... <--- this happens before this snippet 1 1.5 1 ... 10 <--- bottom of my form, after snippet 1.5 2 <--- beginning of part that runs again! ... 9 <--- this happens after this snippet I've searched my codebase high and low, but there is NOTHING that says that it should re-render part of a page. I'm wondering if the jQueryUI has anything to do with it, as #new-ad-form is the container for a jQueryUI dialog box. If this is potentially the case, here's my init code for that: $('#new-ad-form').dialog({ autoOpen: false, modal: true, width: 470, title: 'Create A New Ad', position: ['center', 35], close: AdEditor.reset });

  Read the article

• Creating spotlight in OpenGL scene

  - by Victor Oliveira

  Im studying OpenGL and trying to create a spot light at my application. The code that Im using for my #vertex-shader is below: #:vertex-shader #{ #version 150 core in vec3 in_pos; in vec2 in_tc; out vec2 tc; glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 20.0f); GLfloat spot_direction[] = { -1.0, -1.0, 0.0 }; glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, spot_direction); glEnable(GL_LIGHT0); void main() { vec4 pos= vec4(vec3(1.0)*in_pos - vec3(1.0), 1.0); pos.z=0.0; gl_Position = pos; tc = in_tc; } } The thing is, everytime Im trying to run the code an Error that says: Type: other, Source: api, ID: 131169, Severity: low Message: Framebuffer detailed info: The driver allocated storage for renderbuffer 1. len = 157, written = 0 failed to compile vertex shader of deferred: directional info log for shader deferred: directional vertex info log for shader deferred: directional: ERROR: Unbound variable: when Specifications: Renderer: GeForce GTX 580/PCIe/SSE2 Version: 3.3.0 NVIDIA 319.17 GLSL: 3.30 NVIDIA via Cg compiler Status: Using GLEW 1.9.0 1024 x 768 OS: Linux debian I guess to create this spotlight is pretty much simple, but since Im really new to OpenGL I dont have a clue how to do it until now, even reading sources like: http://www.glprogramming.com/red/chapter05.html#name3 Read also in some place that light spots can get really hard to understand, but I cant avoid this step right now since Im following my lecture schedule. Could anybody help me?

  Read the article

• Generate a set of strings with maximum edit distance

  - by Kevin Jacobs

  Problem 1: I'd like to generate a set of n strings of fixed length m from alphabet s such that the minimum Levenshtein distance (edit distance) between any two strings is greater than some constant c. Obviously, I can use randomization methods (e.g., a genetic algorithm), but was hoping that this may be a well-studied problem in computer science or mathematics with some informative literature and an efficient algorithm or three. Problem 2: Same as above except that adjacent characters cannot repeat; the i'th character in each string may not be equal to the i+1'th character. E.g., 'CAT', 'AGA' and 'TAG' are allowed, 'GAA', 'AAT', and 'AAA' are not. Background: The basis for this problem is bioinformatic and involves designing unique DNA tags that can be attached to biologically derived DNA fragments and then sequenced using a fancy second generation sequencer. The goal is to be able to recognize each tag, allowing for random insertion, deletion, and substitution errors. The specific DNA sequencing technology has a relatively low error rate per base (~1%), but is less precise when a single base is repeated 2 or more times (motivating the additional constraints imposed in problem 2).

  Read the article

• Saving complex aggregates using Repository Pattern

  - by Kevin Lawrence

  We have a complex aggregate (sensitive names obfuscated for confidentiality reasons). The root, R, is composed of collections of Ms, As, Cs, Ss. Ms have collections of other low-level details. etc etc R really is an aggregate (no fair suggesting we split it!) We use lazy loading to retrieve the details. No problem there. But we are struggling a little with how to save such a complex aggregate. From the caller's point of view: r = repository.find(id); r.Ps.add(factory.createP()); r.Cs[5].updateX(123); r.Ms.removeAt(5); repository.save(r); Our competing solutions are: Dirty flags Each entity in the aggregate in the aggregate has a dirty flag. The save() method in the repository walks the tree looking for dirty objects and saves them. Deletes and adds are a little trickier - especially with lazy-loading - but doable. Event listener accumulates changes. Repository subscribes a listener to changes and accumulates events. When save is called, the repository grabs all the change events and writes them to the DB. Give up on repository pattern. Implement overloaded save methods to save the parts of the aggregate separately. The original example would become: r = repository.find(id); r.Ps.add(factory.createP()); r.Cs[5].updateX(123); r.Ms.removeAt(5); repository.save(r.Ps); repository.save(r.Cs); repository.save(r.Ms); (or worse) Advice please! What should we do?

  Read the article

• DSP - Filtering frequencies using DFT

  - by Trap

  I'm trying to implement a DFT-based 8-band equalizer for the sole purpose of learning. To prove that my DFT implementation works I fed an audio signal, analyzed it and then resynthesized it again with no modifications made to the frequency spectrum. So far so good. I'm using the so-called 'standard way of calculating the DFT' which is by correlation. This method calculates the real and imaginary parts both N/2 + 1 samples in length. To attenuate a frequency I'm just doing: float atnFactor = 0.6; Re[k] *= atnFactor; Im[k] *= atnFactor; where 'k' is an index in the range 0 to N/2, but what I get after resynthesis is a slighty distorted signal, especially at low frequencies. The input signal sample rate is 44.1 khz and since I just want a 8-band equalizer I'm feeding the DFT 16 samples at a time so I have 8 frequency bins to play with. Can someone show me what I'm doing wrong? I tried to find info on this subject on the internet but couldn't find any. Thanks in advance.

  Read the article

• Altruistic network connection bandwidth estimation

  - by datenwolf

  Assume two peers Alice and Bob connected over a IP network. Alice and Bob are exchanging packets of lossy compressed data which are generated and to be consumes in real time (think a VoIP or video chat application). The service is designed to cope with as little bandwidth available, but relies on low latencies. Alice and Bob would mark their connection with an apropriate QoS profile. Alice and Bob want use a variable bitrate compression and would like to consume all of the leftover bandwidth available for the connection between them, but would voluntarily reduce the consumed bitrate depending on the state of the network. However they'd like to retain a stable link, i.e. avoid interruptions in their decoded data stream caused by congestion and the delay until the bandwidth got adjusted. However it is perfectly possible for them to loose a few packets. TL;DR: Alice and Bob want to implement a VoIP protocol from scratch, and are curious about bandwidth and congestion control. What papers and resources do you suggest for Alice and Bob to read? Mainly in the area of bandwidth estimation and congestion control.

  Read the article

• How to test a struts 2.1.x developer?

  - by Jason Pyeron

  We employ test to filter out those who can't. The tests are designed to be very low effort for those who can and too much effort for those who can't. Here is an example for java web application developer on an Oracle project: We only work with contractors who can use the tools we use, to determine if you can use the tools we have devised some very simple tests. Instructions If you are prepared and knowledgeable this will take you about 2-5 minutes. Suggested knowledge and tools: * subversion 1.6 see http://subversion.tigris.org/ or http://cygwin.com/setup.exe * java 1.6 see http://java.sun.com/javase/downloads/index.jsp * oracle >=10g see http://www.oracle.com/technology/software/products/jdev/index.html * j2ee server see http://tomcat.apache.org/download-55.cgi or http://www.jboss.org/jbossas/downloads/ Steps 1. check out svn://statics32.pdinc.us/home/subversion/guest 2. deploy the war file found at trunk/test.war 3. browse to the web application you installed from the war file and answer the one SQL question: How many rows are in the table 'testdata' where column 'value' ends with either an 'A' or an 'a'? The login credentials are in trunk/doc/oracle.txt 4. make a RESULTS HASH by submitting your answer to the form. 5. create a file in tmp/YourUserName.txt and put the RESULTS HASH in it, not the answer. 6. check in your file (don't forget to add the file first). 7. message me with the revision number of your check in. As such I am looking for ideas on how to test for someone to be a struts 2.1 w/ annotations.

  Read the article

• C#.NET DataGridView - update database

  - by Geo Ego

  I know this is a basic function of the DataGridView, but for some reason, I just can't get it to work. I just want the DataGridView on my Windows form to submit any changes made to it to the database when the user clicks the "Save" button. On form load, I populate the DataGridView and that's working fine. In my save function, I basically have the following (I've trimmed out some of the code around it to get to the point): using (SqlDataAdapter ruleTableDA = new SqlDataAdapter("SELECT rule.fldFluteType AS [Flute], rule.fldKnife AS [Knife], rule.fldScore AS [Score], rule.fldLowKnife AS [Low Knife], rule.fldMatrixScore AS [Matrix Score], rule.fldMatrix AS [Matrix] FROM dbo.tblRuleTypes rule WHERE rule.fldMachine_ID = '1003'", con)) { SqlCommandBuilder commandBuilder = new SqlCommandBuilder(ruleTableDA); DataTable dt = new DataTable(); dt = RuleTable.DataSource as DataTable; ruleTableDA.Fill(dt); ruleTableDA.Update(dt); } Okay, so I edited the code to do the following: build the commands, create a DataTable based on the DataGridView (RuleTable), fill the DataAdapter with the DataTable, and update the database. Now ruleTableDA.Update(dt) is throwing the exception "Concurrency violation: the UpdateCommand affected 0 of the expected 1 records." Thanks very much!

  Read the article

• Handling XMLHttpRequest to call external application

  - by Ian

  I need a simple way to use XMLHttpRequest as a way for a web client to access applications in an embedded device. I'm getting confused trying to figure out how to make something thin and light that handles the XMLHttpRequests coming to the web server and can translate those to application calls. The situation: The web client using Ajax (ExtJS specifically) needs to send and receive asynchronously to an existing embedded application. This isn't just to have a thick client/thin server, the client needs to run background checking on the application status. The application can expose a socket interface, with a known set of commands, events, and configuration values. Configuration could probably be transmitted as XML since it comes from a SQLite database. In between the client and app is a lighttpd web server running something that somehow handles the translation. This something is the problem. What I think I want: Lighttpd can use FastCGI to route all XMLHttpRequest to an external process. This process will understand HTML/XML, and translate between that and the application's language. It will have custom logic to simulate pushing notifications to the client (receive XMLHttpRequest, don't respond until the next notification is available). C/C++. I'd really like to avoid installing Java/PHP/Perl on an embedded device. So I'll need more low level understanding. How do I do this? Are there good C++ libraries for interpreting the CGI headers and HTML so that I don't have to do any syntax processing, I can just deal with the request/response contents? Are there any good references to exactly what goes on, server side, when handling the XMLHttpRequest and CGI interfaces? Is there any package that does most of this job already, or will I have to build the non-HTTP/CGI stuff from scratch? Thanks for any help! I am really having trouble learning about the server side of these technologies.

  Read the article

• Improving field get and set performance with ASM or Javassist

  - by ng

  I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM and Javasist examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and one with Javassist? Any help would be greatly appreciated.

  Read the article

• Non-latin-characters ordering in database with "order by"

  - by nybon

  I just found some strange behavior of database's "order by" clause. In string comparison, I expected some characters such as '[' and '_' are greater than latin characters such as 'i' considering their orders in the ASCII table. However, the sorting results from database's "order by" clause is different with my expectation. Here's my test: SQLite version 3.6.23 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite> create table products(name varchar(10)); sqlite> insert into products values('ipod'); sqlite> insert into products values('iphone'); sqlite> insert into products values('[apple]'); sqlite> insert into products values('_ipad'); sqlite> select * from products order by name asc; [apple] _ipad iphone ipod This behavior is different from Java's string comparison (which cost me some time to find this issue). I can verify this in both SQLite 3.6.23 and Microsoft SQL Server 2005. I did some web search but cannot find any related documentation. Could someone shed me some light on it? Is it a SQL standard? Where can I find some information about this? Thanks in advance.

  Read the article

• How to choose light version of databse system

  - by adopilot

  I am starting one POS (Point of sale) project. Targeting system is going to be written in C# .NET 2 WinForms and as main database server We are going to use MS-SQL Server. As we have a lot of POS devices in chain for one store I will love to have backend local data base system on each POS device. Scenario are following: When main server goes down!! POS application should continue working "off-line" with local database, until connection to main server come up again. Now I am in dilemma which local database is going to be most adoptable for me. Here is some notes for helping me point me in right direction: To be Light "My POS devices art usually old and suffering with performances" To be Free "I have a lot of devices and I do not wont additional cost beside main SQL serer" One day Ill love to try all that port on Mono and Linux OS. Here is what I've researched so far: Simple XML "Light but I am afraid of performance, My main table of items is average of 10K records" SQL-Expres "I am afraid that my POS devices is poor with hardware for SQLExpres, and also hard to install on each device and configure" Less known Advantage Database Server have free distribution of offline ADT system. DBF with extended Library,"Respect for good old DBFs but that era is behind Me with clipper and DBFs" MS Access Sqlite "Mostly like for now, but I am afraid how it is going to pair with MS SQL do they have same Data taypes". I know that in this SO is a lot of subjective data, but at least can someone recommended some others lite database system, or things that I shod most take attention before I choice database.

  Read the article

• How to generate random numbers of lognormal distribution within specific range in Matlab

  - by Harpreet

  My grain sizes are defined as D=[1.19,1.00,0.84,0.71,0.59,0.50,0.42]. The problem is described below in steps. Grain sizes should follow lognormal distribution. The mean of the grain sizes is fixed as 0.84 and the standard deviation should be as low as possible but not zero. 90% of the grains (by weight %) fall in the size range of 1.19 to 0.59, and the rest 10% fall in size range of 0.50 to 0.42. Now I want to find the probabilities (weight percentage) of the grains falling in each grain size. It is allowable to split this grain size distribution into further small sizes but it must always be in the range of 1.19 and 0.42, i.e. 'D' can be continuous but 0.42 < D < 1.19. I need it fast. I tried on my own but I am not able to get the correct result. I am getting negative probabilities (weight percentages). Thanks to anyone who helps. I didn't incorporate the point 3 as I came to know about that condition later. Here are simple steps I tried: %% D=[1.19,1.00,0.84,0.71,0.59,0.50,0.42]; s=0.30; % std dev of the lognormal distribution m=0.84; % mean of the lognormal distribution mu=log(m^2/sqrt(s^2+m^2)); % mean of the associated normal dist. sigma=sqrt(log((s^2/m^2)+1)); % std dev of the associated normal dist. [r,c]=size(D); for i=1:c D(i)=mu+(sigma.*randn(1)); w(i)=(log(D(i))-mu)/sigma; % the probability or the wt. percentage of the grain sizes end grain_size=exp(D); %%

  Read the article

• Have I taken a wrong path in programming by being excessively worried about code elegance and style?

  - by Ygam

  I am in a major stump right now. I am a BSIT graduate, but I only started actual programming less than a year ago. I observed that I have the following attitude in programming: I tend to be more of a purist, scorning unelegant approaches to solving problems using code I tend to look at anything in a large scale, planning everything before I start coding, either in simple flowcharts or complex UML charts I have a really strong impulse on refactoring my code, even if I miss deadlines or prolong development times I am obsessed with good directory structures, file naming conventions, class, method, and variable naming conventions I tend to always want to study something new, even, as I said, at the cost of missing deadlines I tend to see software development as something to engineer, to architect; that is, seeing how things relate to each other and how blocks of code can interact (I am a huge fan of loose coupling) i.e the OOP thinking I tend to combine OOP and procedural coding whenever I see fit I want my code to execute fast (thus the elegant approaches and refactoring) This bothers me because I see my colleagues doing much better the other way around (aside from the fact that they started programming since our first year in college). By the other way around I mean, they fire up coding, gets the job done much faster because they don't have to really look at how clean their codes are or how elegant their algorithms are, they don't bother with OOP however big their projects are, they mostly use web APIs, piece them together and voila! Working code! CLients are happy, they get paid fast, at the expense of a really unmaintainable or hard-to-read code that lacks structure and conventions, or slow executions of certain actions (which the common reasoning against would be that internet connections are much faster these days, hardware is more powerful). The excuse I often receive is clients don't care about how you write the code, but they do care about how long you deliver it. If it works then all is good. Now, did my "purist" approach to programming may have been the wrong way to start programming? Should I just dump these purist concepts and just code the hell up because I have seen it: clients don't really care how beautifully coded it is?

  Read the article

• DVCS with a Windows central repository

  - by Mikko Rantanen

  We are currently using VSS for version control. Quite few of our developers are interested in a distributed model (And want to get rid of VSS). Our network is full of Windows machines and while our IT department has experience maintaining Linux machines they would prefer not to. What DVCS systems can host their central repository on Windows while providing.. Push access to the repository. Basic authentication. Mostly just a way to allow or deny access to the whole repository. No need for fine grained access. Server process so users don't need write right to the repository reducing the risk of accidentally messing with it. On the client side a GUI such as Tortoise would be more or less a requirement (Sorry, Windows shell sucks. :|). Ease of installation would be a huge plus as our IT department is already quite low on resources. And using windows credentials for authentication would be an advantage but not a requirement as long as the client is able to store the credentials. I have had a (really) quick look at Git, Mercurial and Bazaar. Git seemed to use ssh or simple WebDAV for repository access, requiring write permission for the users. Mercurial had a built in http server, but this seemed to be only for pull purposes. Update: Mercurial supports push as well. Bazaar Seemed to use sftp for repository access, again requiring a write permission for the users. Are there windows server processes for any DVCS systems and has anyone managed to set one up in a Windows land? And apologies if this is a duplicate question. I couldn't find one. Update Got Mercurial working for push purposes! Detailed list what was required can be found as an answer below.

  Read the article

• How to handle refunds or rebates via a payment processor?

  - by Tai Squared

  I need to handle online payments and am trying to choose a payment processor. One requirement is to handle refunds and rebates to the customer. These won't always be at the time of sale, and not for the entire amount of the purchase. Is this something all payment processors handle? I don't want to have to do this manually as there may be many rebates, and they may be for relatively small amounts. I see PayPal has a refund API, but other parts of their site talk about sending a refund within 60 days. Is this something also required by the API? Amazon FPS also has a refund API that seems a bit more flexible. The Google Checkout refund has an amout field, but it's unclear to me if you can do a partial refund as the description reads "The refund-order command instructs Google Checkout to refund the buyer for a particular order." What are some things to look out for when looking for a payment processor that can handle rebates and refunds? Is there always a time limit in issuing these refunds? Is using a merchant account better for this type of process? I was hoping to avoid that due to the increased cost and complexity, but would consider it if it meets all of my requirements. Update It appears the refund process is fairly simple and handled by all processors. Is there any additional information on rebates? I would like to avoid a process of sending live checks to customers, but I will have to send rebates in some small amounts that may be a few months after the initial purchase.

  Read the article

• Payment Processors - What do I need to know if I want to accept credit cards on my website?

  - by Michael Pryor

  This question talks about different payment processors and what they cost, but I'm looking for the answer to what do I need to do if I want to accept credit card payments? Assume I need to store credit card numbers for customers, so that the obvious solution of relying on the credit card processor to do the heavy lifting is not available. PCI Data Security, which is apparently the standard for storing credit card info, has a bunch of general requirements, but how does one implement them? And what about the vendors, like Visa, who have their own best practices? Do I need to have keyfob access to the machine? What about physically protecting it from hackers in the building? Or even what if someone got their hands on the backup files with the sql server data files on it? What about backups? Are there other physical copies of that data around? Tip: If you get a merchant account, you should negotiate that they charge you "interchange-plus" instead of tiered pricing. With tiered pricing, they will charge you different rates based on what type of Visa/MC is used -- ie. they charge you more for cards with big rewards attached to them. Interchange plus billing means you only pay the processor what Visa/MC charges them, plus a flat fee. (Amex and Discover charge their own rates directly to merchants, so this doesn't apply to those cards. You'll find Amex rates to be in the 3% range and Discover could be as low as 1%. Visa/MC is in the 2% range). This service is supposed to do the negotiation for you (I haven't used it, this is not an ad, and I'm not affiliated with the website, but this service is greatly needed.) This blog post gives a complete rundown of handling credit cards (specifically for the UK).

  Read the article

• Problem with load testing Web Service - VSTS 2008

  - by Carlos

  Hello, I have a webtest with makes a simple call to a WebService which looks like that: MyWebService webService = new MyWebService(); webService.Timeout = 180000; webService.myMethod(); I am not using ThinkTimes, also the Run Duration is set to 5 minutes. When I ran this test simulating only 1 user, I check the counters and I found something like that: Tests Total: 4500 Network Interface\Bytes sent (agent machine): 35,500 Then I ran the same tests, but this time simulating 2 users and I got something like that: Tests Total: 2225 Network Interface\Bytes sent (agent machine): 30,500 So when I increased the numbers of users the tests/sec was half than when I use only 1 user and the bytes sent by the agent was also lower. I think it is strange, because it doesn't seems I have a bottleneck in my agent machine since CPU is never higher than 30% and I have over 1.5GB of RAM free, also my network utilization is like 0.5% of its capacity. In order to troubleshot this I ran a test using Step Pattern, the simulated users went from 20 to 800 users. When I check the requests/sec it is practically constant through the whole test, so it is clear there is something in my test or my environment which is preventing the number of requests from gets higher. It would be a expected behavior if the "response time" was getting higher because it would tell me the requests wasn't been processed properly, but the strange thing is the response time is practically constant all the time and it is pretty low actually. I have no idea why my agent can't send more requests when I increase the numbers of users, any help/tip/guess would be really appreciate.

  Read the article

< Previous Page | 241 242 243 244 245 246 247 248 249 250 251 252  | Next Page >