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• Am I making the right choice in choosing Yii as my PHP Framework?

  - by Bara

  I am about to begin development of a new website and have been doing research on PHP Frameworks. I'm not an advanced PHP developer, but I have been developing web sites and apps (in asp.net) for a few years now. My website will primarily be AJAX-based (using jQuery) and making lots of calls to web services. After some research, here's what I came up with: CakePHP: Originally started developing in this, but found it too complex. The fact that it forces you to use and learn all this new stuff just to use it was a bit daunting, so I put it aside for the time being. Zend: The performance of the framework leaves me a bit skeptical, but I heard it has great support for creating web services. I also heard it was a bit complex. CodeIgniter: No real reason for not using this one. Based on what I've read CodeIgniter and Yii are very similar, but Yii is a bit faster and doesn't have un-needed code for PHP4 (since I plan on developing exclusively in PHP5). As far as Yii, the only things that scare me about it are that it is newer than the other frameworks so it has a smaller community. It also doesn't seem to have a ton of web service support (only SOAP, from my understanding) as opposed to Zend. So my questions come down to: Should these things worry me? (not as big of a community, poor web service support) Is there anything else I should look into? Is my choice of Yii over the other frameworks ok for a primarily AJAX-based web app? Bara

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• Generating a field setter and getter with ASM

  - 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 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 maybe one with Javassist? Any help would be greatly appreciated.

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• Events and references pattern

  - by serhio

  In a project I have the following relation between BO and GUI By e.g. G could represent a graphic with time lines, C a TimeLine curve, P - points of that curve and T the time that represents each point. Each GUI object is associated with the BO corresponding object. When T changes GUI P captures the Changed event and changes its location. So, when G should be modified, it modifies internally its objects and as result T changes, P moves and the GuiG visually changes, everything is OK. But there is an inconvenient of this architecture... BO should not be recreated, because this will breack the link between BO and GUIO. In particular, GUI P should always have the same reference of T. If in a business logic I do by e.g. P1.T = new T(this.T + 10) GUI_P1 will not move anymore, because it wait an event from the reference of former P1.T object, that does not belongs to P1 anymore. So the solution was to always modify the existing objects, not to recreate it. But here is an other inconvenient: performance. Say I have a ready newC object that should replace the older one. Instead of doing G1.C = newC I should do foreach T in foreach P in C replace with T from P from newC. Is there an other more optimal way to do it?

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• High Runtime for Dictionary.Add for a large amount of items

  - by aaginor

  Hi folks, I have a C#-Application that stores data from a TextFile in a Dictionary-Object. The amount of data to be stored can be rather large, so it takes a lot of time inserting the entries. With many items in the Dictionary it gets even worse, because of the resizing of internal array, that stores the data for the Dictionary. So I initialized the Dictionary with the amount of items that will be added, but this has no impact on speed. Here is my function: private Dictionary<IdPair, Edge> AddEdgesToExistingNodes(HashSet<NodeConnection> connections) { Dictionary<IdPair, Edge> resultSet = new Dictionary<IdPair, Edge>(connections.Count); foreach (NodeConnection con in connections) { ... resultSet.Add(nodeIdPair, newEdge); } return resultSet; } In my tests, I insert ~300k items. I checked the running time with ANTS Performance Profiler and found, that the Average time for resultSet.Add(...) doesn't change when I initialize the Dictionary with the needed size. It is the same as when I initialize the Dictionary with new Dictionary(); (about 0.256 ms on average for each Add). This is definitely caused by the amount of data in the Dictionary (ALTHOUGH I initialized it with the desired size). For the first 20k items, the average time for Add is 0.03 ms for each item. Any idea, how to make the add-operation faster? Thanks in advance, Frank

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• How can I handle dynamic calculated attributes in a model in Django?

  - by bullfish

  In Django I calculate the breadcrumb (a list of fathers) for an geographical object. Since it is not going to change very often, I am thinking of pre calculating it once the object is saved or initialized. 1.) What would be better? Which solution would have a better performance? To calculate it at _init_ or to calculate it when the object is saved (the object takes about 500-2000 characters in the DB)? 2.) I tried to overwrite the _init_ or save() methods but I don't know how to use attributes of the just saved object. Accessing *args, **kwargs did not work. How can I access them? Do I have to save, access the father and then save again? 3.) If I decide to save the breadcrumb. Whats the best way to do it? I used http://www.djangosnippets.org/snippets/1694/ and have crumb = PickledObjectField(). Thats the method to calculate the attribute crumb() def _breadcrumb(self): breadcrumb = [ ] x = self while True: x = x.father try: if hasattr(x, 'country'): breadcrumb.append(x.country) elif hasattr(x, 'region'): breadcrumb.append(x.region) elif hasattr(x, 'city'): breadcrumb.append(x.city) else: break except: break breadcrumb.reverse() return breadcrumb Thats my save-Method: def save(self,*args, **kwargs): # how can I access the father ob the object? father = self.father # does obviously not work father = kwargs['father'] # does not work either # the breadcrumb gets calculated here self.crumb = self._breadcrumb(father) super(GeoObject, self).save(*args,**kwargs) Please help me out. I am working on this for days now. Thank you.

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• How does someone without a CS degree get an interview in a sluggish economy?

  - by Anon

  I've been programming off and on since 4th grade (for about 20 years). Technology is one of my passions but after working in the field for a couple years out of High School, I spent nine months and $15,000 getting an accredited certificate in music performance instead of CS. I've been doing lots of self study but I think a CS degree is overkill for most line of business applications. Even so, HR departments can't be expected to know that... How does one get their foot in the proverbial door without a degree, especially in a smaller "fly-over country" market? ...or... Where can I get the cheapest/easiest degree that will pass muster (including testing out of as much as possible)? Don't get me wrong, I'm down with learning new things but I don't necessarily need the expense or coaching to motivate me. EDIT Consolidating good answers: Networking/User Groups Portfolio/Open Source Contributions Look for hybrid jobs (How I got my start :) ) Seek un-elitist companies/hiring managers. (Play the numbers game) Start my own business. (This is a bit challenging for a family man but a very good answer. My reason for searching is to reduce my commute thereby allowing more time to cultivate income on the side) Avail myself of political subsidies to constituents in the teachers' unions ;) .

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• How to efficiently convert String, integer, double, datetime to binary and vica versa?

  - by Ben

  Hi, I'm quite new to C# (I'm using .NET 4.0) so please bear with me. I need to save some object properties (their properties are int, double, String, boolean, datetime) to a file. But I want to encrypt the files using my own encryption, so I can't use FileStream to convert to binary. Also I don't want to use object serialization, because of performance issues. The idea is simple, first I need to somehow convert objects (their properties) to binary (array), then encrypt (some sort of xor) the array and append it to the end of the file. When reading first decrypt the array and then somehow convert the binary array back to object properties (from which I'll generate objects). I know (roughly =) ) how to convert these things by hand and I could code it, but it would be useless (too slow). I think the best way would be just to get properties' representation in memory and save that. But I don't know how to do it using C# (maybe using pointers?). Also I though about using MemoryStream but again I think it would be inefficient. I am thinking about class Converter, but it does not support toByte(datetime) (documentation says it always throws exception). For converting back I think the only options is class Converter. Note: I know the structure of objects and they will not change, also the maximum String length is also known. Thank you for all your ideas and time. EDIT: I will be storing only parts of objects, in some cases also parts of different objects (a couple of properties from one object type and a couple from another), thus I think that serialization is not an option for me.

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• PHP Socket Server vs node.js: Web Chat

  - by Eliasdx

  I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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• Pump Messages During Long Operations + C# (it is urgent)

  - by Newbie

  Hi I have a web service that is doing huge computation and is taking more than a minute. I have generated the proxy file of the web service and then from my client end I am using the dll(of course I generated the proxy dll). My client side code is TimeSeries3D t = new TimeSeries3D(); int portfolioId = 4387919; string[] str = new string[2]; str[0] = "MKT_CAP"; DateRange dr = new DateRange(); dr.mStartDate = DateTime.Today; dr.mEndDate = DateTime.Today; Service1 sc = new Service1(); t = sc.GetAttributesForPortfolio(portfolioId, true, str, dr); But since it is taking to much time for the server to compute, after 1 minute I am receiving an error message The CLR has been unable to transition from COM context 0x33caf30 to COM context 0x33cb0a0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. Kindly guide me what to do? It is very urgent. Thanks

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• Generic InBetween Function.

  - by Luiscencio

  I am tired of writing x > min && x < max so i wawnt to write a simple function but I am not sure if I am doing it right... actually I am not cuz I get an error: bool inBetween<T>(T x, T min, T max) where T:IComparable { return (x > min && x < max); } errors: Operator '>' cannot be applied to operands of type 'T' and 'T' Operator '<' cannot be applied to operands of type 'T' and 'T' may I have a bad understanding of the where part in the function declaring note: for those who are going to tell me that I will be writing more code than before... think on readability =) any help will be appreciated EDIT deleted cuz it was resolved =) ANOTHER EDIT so after some headache I came out with this (ummm) thing following @Jay Idea of extreme readability: public static class test { public static comparision Between<T>(this T a,T b) where T : IComparable { var ttt = new comparision(); ttt.init(a); ttt.result = a.CompareTo(b) > 0; return ttt; } public static bool And<T>(this comparision state, T c) where T : IComparable { return state.a.CompareTo(c) < 0 && state.result; } public class comparision { public IComparable a; public bool result; public void init<T>(T ia) where T : IComparable { a = ia; } } } now you can compare anything with extreme readability =) what do you think.. I am no performance guru so any tweaks are welcome

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• Are Dynamic Prepared Statements Bad? (with php + mysqli)

  - by John

  I like the flexibility of Dynamic SQL and I like the security + improved performance of Prepared Statements. So what I really want is Dynamic Prepared Statements, which is troublesome to make because bind_param and bind_result accept "fixed" number of arguments. So I made use of an eval() statement to get around this problem. But I get the feeling this is a bad idea. Here's example code of what I mean // array of WHERE conditions $param = array('customer_id'=>1, 'qty'=>'2'); $stmt = $mysqli->stmt_init(); $types = ''; $bindParam = array(); $where = ''; $count = 0; // build the dynamic sql and param bind conditions foreach($param as $key=>$val) { $types .= 'i'; $bindParam[] = '$p'.$count.'=$param["'.$key.'"]'; $where .= "$key = ? AND "; $count++; } // prepare the query -- SELECT * FROM t1 WHERE customer_id = ? AND qty = ? $sql = "SELECT * FROM t1 WHERE ".substr($where, 0, strlen($where)-4); $stmt->prepare($sql); // assemble the bind_param command $command = '$stmt->bind_param($types, '.implode(', ', $bindParam).');'; // evaluate the command -- $stmt->bind_param($types,$p0=$param["customer_id"],$p1=$param["qty"]); eval($command); Is that last eval() statement a bad idea? I tried to avoid code injection by encapsulating values behind the variable name $param. Does anyone have an opinion or other suggestions? Are there issues I need to be aware of?

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• Google Adwords API response parse

  - by Yun Ling

  I am trying to figure out how to parse the Adword API query response without exceptions and one issue that i came across is that sometimes, the data itself contains comma besides the comma between each column. Say i do a query on Adroup, campaign and impression by using <reportDefinition xmlns="https://adwords.google.com/api/adwords/cm/v201209"> <selector> <fields>CampaignName</fields> <fields>AdgroupName</fields> <fields>Impressions</fields> <predicates> <field>Status</field> <operator>IN</operator> <values>ENABLED</values> <values>PAUSED</values> </predicates> </selector> <reportName>Custom Adgroup Performance Report</reportName> <reportType>ADGROUP_PERFORMANCE_REPORT</reportType> <dateRangeType>LAST_7_DAYS</dateRangeType> <downloadFormat>CSV</downloadFormat> </reportDefinition> Since my campaign has comma within the string like below: "Adroup,Campaign,Impressions, Premiun Beer, Beer, Chicago, 1000" where the adgroup is "premium beer" and campaign is "Beer,Chicago". that will cause an issue if we parse this information by using comma. Does anyone know how to solve this problem?

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• Flex web application: prevent framerate drop when window is invisible

  - by JayPea

  So there's been a new "feature" in the flash player since version 10.1, which reduces the player's framerate to 2 fps when the application window is out of view. This is good news for performance, but it can break some functionality, such as the Timer class. I have an application which uses a Timer to display a countdown. Given the nature of the application, it is required for the Timer to complete its countdown even if the user is not there to see it. Imagine that you need to give the user only 10 seconds to perform a task. If the user minimizes the window halfway through the counter, they can take as much time as they want and still have 5 seconds left when they return to the window. This apparently can not be avoided with the newer flash players. In Air applications there is the backgroundFrameRate property which can be set to prevent this behavior, but this is part of the WindowedApplication class, so it seems that it is not available in a web application. Does anyone know a way to keep a constant frame rate even when the window is not visible? Thanks

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• Why would this Lua optimization hack help?

  - by Ian Boyd

  i'm looking over a document that describes various techniques to improve performance of Lua script code, and i'm shocked that such tricks would be required. (Although i'm quoting Lua, i've seen similar hacks in Javascript). Why would this optimization be required: For instance, the code for i = 1, 1000000 do local x = math.sin(i) end runs 30% slower than this one: local sin = math.sin for i = 1, 1000000 do local x = sin(i) end They're re-declaring sin function locally. Why would this be helpful? It's the job of the compiler to do that anyway. Why is the programmer having to do the compiler's job? i've seen similar things in Javascript; and so obviously there must be a very good reason why the interpreting compiler isn't doing its job. What is it? i see it repeatedly in the Lua environment i'm fiddling in; people redeclaring variables as local: local strfind = strfind local strlen = strlen local gsub = gsub local pairs = pairs local ipairs = ipairs local type = type local tinsert = tinsert local tremove = tremove local unpack = unpack local max = max local min = min local floor = floor local ceil = ceil local loadstring = loadstring local tostring = tostring local setmetatable = setmetatable local getmetatable = getmetatable local format = format local sin = math.sin What is going on here that people have to do the work of the compiler? Is the compiler confused by how to find format? Why is this an issue that a programmer has to deal with? Why would this not have been taken care of in 1993? i also seem to have hit a logical paradox: Optimizatin should not be done without profiling Lua has no ability to be profiled Lua should not be optimized

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• Is there any appreciable difference between if and if-else?

  - by Drew

  Given the following code snippets, is there any appreciable difference? public boolean foo(int input) { if(input > 10) { doStuff(); return true; } if(input == 0) { doOtherStuff(); return true; } return false; } vs. public boolean foo(int input) { if(input > 10) { doStuff(); return true; } else if(input == 0) { doOtherStuff(); return true; } else { return false; } } Or would the single exit principle be better here with this piece of code... public boolean foo(int input) { boolean toBeReturned = false; if(input > 10) { doStuff(); toBeReturned = true; } else if(input == 0) { doOtherStuff(); toBeReturned = true; } return toBeReturned; } Is there any perceptible performance difference? Do you feel one is more or less maintainable/readable than the others?

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• VB6 Game Development

  - by CVS-2600Hertz-wordpress-com

  Hi All, I am developing a game in VB6 (plz don't ask me why :) ). The storyboard is ready and a rough implementation is underway. I am following a "pure-software-rendering" approach. (i.e. no DirectX, no openGL etc.) Amongst many others, the following "serious" problems exist: 2D alpha transparency reqd. to implement overlays. Parallax implementation to give depth-of-field illusion. Capturing mouse-scroll events globally (as in FPS-es; mapping them to changing weapon). Async sound play with absolute "near-zero-lag". Any ideas anyone. Please suggest any well documented library/ocx or sample-code. Plz do suggest solutions with good performance and as little overhead as possible. Also, anyone who has developed any games, and would be open to sharing her/his code would be highly appreciated. (any well-acknowledged VB games whose source-code i can study??) UPDATE: Here is a screen shot of GearHead Garage. This picture ought to describe what i was attempting in words above... :) Thank You

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• Possible to capture all events in a web browser?

  - by David

  I am working on a pet project and am at the research stage. Quick summary I am trying to intercept all form submits, onclick, and every single keydown. My library of choice is either jquery, or jquery + prototypejs. I figure I can batch up the events into a queue/stack and send it back to the server in time interval batches to keep performance relatively stable. Concerns Form submits and change's would be relatively simple.. Something like $("form :inputs").bind("change", function() { ... record event... }); But how to ensure I get precedence over the applications handlers as I have a habit of putting return false on a lot of my form handlers when there is a validation issue. As I understand it, that effectively stops the event in its tracks. My project For my smaller remote clients I will put their products onto a VPS or run it in my home data center. Currently I use a basic authentication system, given a username/password they see the website and then hopefully send me somewhat sane notes on what is broken or should be tweaked. As a better solution, I've written a simple proxy web server that does the above but allows me to have one DNS entry and then depending on credentials it makes an internal request relaying headers and re-writing URLS as needed. Every single html/text or application/* request is compressed and shoved into a sqlite table so I can partially replay what they've done. Now I am shifting to the frontend and would like to capture clicks, keydown's, and submits on everything on the page.

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• Research and replace Word Rtf

  - by Perello

  I'm working on an application which has a workflow for postal mails. These postal mails are generated according to my application business rules. Models are in html or Rtf and it works perfectly as long the user do not create the rtf with word. This is not within the specs, but my hierarchy would welcome a Word compatibility if it don't involve too much work, and it would please and ease the life of our customer. The Rtf models have tags which are replaced by application values. In most RTF, tags are not splitted, so the search and replace works perfectly. I wish to be handle word with few modifications. Example data : [[FooBuzz]] in most rtf it's not splited. In word 2003 : {\rtlch\fcs1 \af0 \ltrch\fcs0 \insrsid5517131 [[}{\rtlch\fcs1 \af0 \ltrch\fcs0 \insrsid2708730 FooBuzz}{\rtlch\fcs1 \af0 \ltrch\fcs0 \insrsid5517131 ]]} And their word (word 2007) splitted also Foo{garbage inside} Buzz. So i wish to be able to handle common RTF perfectly, and detect tags even if they are splitted. I have 2 constraints. First no regression, second it has to stay simple. Performance is not an issue here. I'm using symfony 1.4. The actual relevant research code part : $regExpression = '/\[\[([^\[\]]*)\]\]/'; preg_match_all($regExpression, $sTemplate, $outKeys);

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• Design patterns for Agent / Actor based concurrent design.

  - by nso1

  Recently i have been getting into alternative languages that support an actor/agent/shared nothing architecture - ie. scala, clojure etc (clojure also supports shared state). So far most of the documentation that I have read focus around the intro level. What I am looking for is more advanced documentation along the gang of four but instead shared nothing based. Why ? It helps to grok the change in design thinking. Simple examples are easy, but in a real world java application (single threaded) you can have object graphs with 1000's of members with complex relationships. But with agent based concurrency development it introduces a whole new set of ideas to comprehend when designing large systems. ie. Agent granularity - how much state should one agent manage - implications on performance etc or are their good patterns for mapping shared state object graphs to agent based system. tips on mapping domain models to design. Discussions not on the technology but more on how to BEST use the technology in design (real world "complex" examples would be great).

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• Rewriting a for loop in pure NumPy to decrease execution time

  - by Statto

  I recently asked about trying to optimise a Python loop for a scientific application, and received an excellent, smart way of recoding it within NumPy which reduced execution time by a factor of around 100 for me! However, calculation of the B value is actually nested within a few other loops, because it is evaluated at a regular grid of positions. Is there a similarly smart NumPy rewrite to shave time off this procedure? I suspect the performance gain for this part would be less marked, and the disadvantages would presumably be that it would not be possible to report back to the user on the progress of the calculation, that the results could not be written to the output file until the end of the calculation, and possibly that doing this in one enormous step would have memory implications? Is it possible to circumvent any of these? import numpy as np import time def reshape_vector(v): b = np.empty((3,1)) for i in range(3): b[i][0] = v[i] return b def unit_vectors(r): return r / np.sqrt((r*r).sum(0)) def calculate_dipole(mu, r_i, mom_i): relative = mu - r_i r_unit = unit_vectors(relative) A = 1e-7 num = A*(3*np.sum(mom_i*r_unit, 0)*r_unit - mom_i) den = np.sqrt(np.sum(relative*relative, 0))**3 B = np.sum(num/den, 1) return B N = 20000 # number of dipoles r_i = np.random.random((3,N)) # positions of dipoles mom_i = np.random.random((3,N)) # moments of dipoles a = np.random.random((3,3)) # three basis vectors for this crystal n = [10,10,10] # points at which to evaluate sum gamma_mu = 135.5 # a constant t_start = time.clock() for i in range(n[0]): r_frac_x = np.float(i)/np.float(n[0]) r_test_x = r_frac_x * a[0] for j in range(n[1]): r_frac_y = np.float(j)/np.float(n[1]) r_test_y = r_frac_y * a[1] for k in range(n[2]): r_frac_z = np.float(k)/np.float(n[2]) r_test = r_test_x +r_test_y + r_frac_z * a[2] r_test_fast = reshape_vector(r_test) B = calculate_dipole(r_test_fast, r_i, mom_i) omega = gamma_mu*np.sqrt(np.dot(B,B)) # write r_test, B and omega to a file frac_done = np.float(i+1)/(n[0]+1) t_elapsed = (time.clock()-t_start) t_remain = (1-frac_done)*t_elapsed/frac_done print frac_done*100,'% done in',t_elapsed/60.,'minutes...approximately',t_remain/60.,'minutes remaining'

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• PreparedStatement question in Java against Oracle.

  - by fardon57

  Hi everyone, I'm working on the modification of some code to use preparedStatement instead of normal Statement, for security and performance reason. Our application is currently storing information into an embedded derby database, but we are going to move soon to Oracle. I've found two things that I need your help guys about Oracle and Prepared Statement : 1- I've found this document saying that Oracle doesn't handle bind parameters into IN clauses, so we cannot supply a query like : Select pokemon from pokemonTable where capacity in (?,?,?,?) Is that true ? Is there any workaround ? ... Why ? 2- We have some fields which are of type TIMESTAMP. So with our actual Statement, the query looks like this : Select raichu from pokemonTable where evolution = TO_TIMESTAMP('2500-12-31 00:00:00.000', 'YYYY-MM-DD HH24:MI:SS.FF') What should be done for a prepared Statement ? Should I put into the array of parameters : 2500-12-31 or TO_TIMESTAMP('2500-12-31 00:00:00.000', 'YYYY-MM-DD HH24:MI:SS.FF') ? Thanks for your help, I hope my questions are clear ! Regards,

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• optimize 2D array in C++

  - by Hristo

  I'm dealing with a 2D array with the following characteristics: const int cols = 500; const int rows = 100; int arr[rows][cols]; I access array arr in the following manner to do some work: for(int k = 0; k < T; ++k) { // for each trainee myscore[k] = 0; for(int i = 0; i < N; ++i) { // for each sample for(int j = 0; j < E[i]; ++j) { // for each expert myscore[k] += delta(i, anotherArray[k][i], arr[j][i]); } } } So I am worried about the array 'arr' and not the other one. I need to make this more cache-friendly and also boost the speed. I was thinking perhaps transposing the array but I wasn't sure how to do that. My implementation turns out to only work for square matrices. How would I make it work for non-square matrices? Also, would mapping the 2D array into a 1D array boost the performance? If so, how would I do that? Finally, any other advice on how else I can optimize this... I've run out of ideas, but I know that arr[j][i] is the place where I need to make changes because I'm accessing columns by columns instead of rows by rows so that is not cache friendly at all. Thanks, Hristo

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• Is it possible to definitively identify whether a DML command was issued from a stored procedure?

  - by Ed Harper

  I have inherited a SQL Server 2008 database to which calling applications have access through stored procedures. Each table in the database has a shadow audit table into which Insert/Update/Delete operations for are logged. Performance testing on populating the audit tables showed that inserting the audit records using OUTPUT clauses was 20% or so faster than using triggers, so this has been implemented in the stored procedures. However, because this design cannot track changes made directly to the tables through DML statements issued directly against the tables, triggers have also been implemented which use the value of @@NESTLEVEL to determine whether or not to run the trigger (the assumption being that all DML run through stored procedures will have @@NESTLEVEL 1). i.e. the body of the trigger code looks something like: IF @@NESTLEVEL = 1 -- implies call is direct sql so generate history from here BEGIN ... insert into audit table This design is flawed because it won't track updates where DML statements are executed in dynamic SQL, or any other context where @@NESTLEVEL is raised above 1. Can anyone suggest a completely reliable method we can use in the triggers to execute them only if not triggered by a stored procedure? Or is this (as I suspect) not possible?

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• How to code a 'Next in Results' within search results in PHP

  - by thebluefox

  Right, bit of a head scratcher, although I've got a feeling there's an obvious answer and I'm just not seeing the wood for the trees. Baiscally, using Solr as a search engine for my site, bringing back 15 results per page. When you click on a result, you get a detail page, that has a "Next in Results" link on it, which obviously forwards you on to the next result. Whats the best way of doing this? I've come up with a few solutions but they're either too inpractical or just don't work. I could store all the ids in a session array, then grab the one after the current one and put that in the link. But with possibly hundreds/thousands of results, the memory that array would need, and the performance hit of dealing with it isn't practical. I could take the same approach and put it into the db, but I'll still have to deal with a potentially huge array when I grab them out of the db. Or; I could do the search again, only returning the id's, and grab the one after the one we're currently looking at. I think this could be the best option? Although it does seem kind of messy, namely because of when I have to select the id thats on a different 'page' (ie the 16th, 31st etc result). Unless I pass through where it was in the results, and select from there, but that still doesn't seem like the right way to do it. I'm really sorry if this is just complete nonsense, any help is massively appreciated as always, Cheers guys!

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• How can I optimize the SELECT statement running on an Oracle database?

  - by Elvis Lou

  I have a SELECT statement in ORACLE: SELECT COUNT(DISTINCT ds1.endpoint_msisdn) multiple30, dss1.service, dss1.endpoint_provisioning_id, dss1.company_scope, Nvl(x.subscription_status, dss1.subscription_status) subscription_status FROM daily_summary ds1 join daily_summary ds2 ON ds1.endpoint_msisdn = ds2.endpoint_msisdn, daily_summary_static dss1, daily_summary_static dss2, (SELECT NULL subscription_status FROM dual UNION ALL SELECT -2 subscription_status FROM dual) x WHERE ds1.summary_ts >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND ds1.summary_ts <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss1.last_active >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND dss1.last_active <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss2.last_active >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND dss2.last_active <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss1.service <> dss2.service AND ( dss1.company_scope = 2 OR dss1.company_scope = 5 ) AND ( dss2.company_scope = 2 OR dss2.company_scope = 5 ) AND dss1.company_scope = dss2.company_scope AND ds1.endpoint_noc_id = dss1.endpoint_noc_id AND ds1.endpoint_host_id = dss1.endpoint_host_id AND ds1.endpoint_instance_id = dss1.endpoint_instance_id AND ds2.endpoint_noc_id = dss2.endpoint_noc_id AND ds2.endpoint_host_id = dss2.endpoint_host_id AND ds2.endpoint_instance_id = dss2.endpoint_instance_id AND dss1.endpoint_provisioning_id = dss2.endpoint_provisioning_id AND Least(1, ds1.total_actions) = 1 AND Least(1, ds2.total_actions) = 1 GROUP BY dss1.service, dss1.endpoint_provisioning_id, dss1.company_scope, Nvl(x.subscription_status, dss1.subscription_status); This query took about 26 minutes to return in my environment, but if I remove the section: dss1.last_active >= to_date('10-04-2012','dd-mm-yyyy') - 30 AND dss1.last_active <= to_date('10-04-2012','dd-mm-yyyy') AND dss2.last_active >= to_date('10-04-2012','dd-mm-yyyy') - 30 AND dss2.last_active <= to_date('10-04-2012','dd-mm-yyyy') AND it only took 20 seconds to run. We have index on the column last_active, I don't know why the section slow down the performance so much? any ideas?

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