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• Finding subsets that can be completed to tuples without duplicates

  - by Jules

  We have a collection of sets A_1,..,A_n. The goal is to find new sets for each of the old sets. newA_i = {a_i in A_i such that there exist (a_1,..,a_n) in (A1,..,An) with no a_k = a_j for all k and j} So in words this says that we remove all the elements from A_i that can't be used to form a tuple (a_1,..a_n) from the sets (A_1,..,A_n) such that the tuple doesn't contain duplicates. My question is how to compute these new sets quickly. If you just implement this definition by generating all possible v's this will take exponential time. Do you know a better algorithm? Edit: here's an example. Take A_1 = {1,2,3,4} A_2 = {2}. Now the new sets look like this: newA_1 = {1,3,4} newA_2 = {2} The 2 has been removed from A_1 because if you choose it the tuple will always be (2,2) which is invalid because it contains duplicates. On the other hand 1,3,4 are valid because (1,2), (3,2) and (4,2) are valid tuples. Another example: A_1 = {1,2,3} A_2 = {1,4,5} A_3 = {2,4,5} A_4 = {1,2,3} A_5 = {1,2,3} Now the new sets are: newA_1 = {1,2,3} newA_2 = {4,5} newA_3 = {4,5} newA_4 = {1,2,3} newA_5 = {1,2,3} The 1 and 2 are removed from sets 2 and 3 because if you choose the 1 or 2 from these sets you'll only have 2 values left for sets 1, 4 and 5, so you will always have duplicates in tuples that look like (_,1,_,_,_) or like (_,_,2,_,_).

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• Flash as3 smooth threshold

  - by arkzai

  hello, I'm building a flash app that pulls images from flickr and removes the white background I'm dong this using threshold and i get a really ragged outcome is there any way to get a better and smoother color key? thanks photoNumber = Math.floor(Math.random() * (photos.length)); loader.load(new URLRequest(photos[photoNumber].path)); loader.contentLoaderInfo.addEventListener(Event.COMPLETE,draw); trace ( "trying to load photo " + photoNumber ); function draw(e:Event) { trace ("show photo " + photoNumber) var W:int=e.target.content.width; var H:int=e.target.content.height; bitmapdata=new BitmapData(W,H); bitmap=new Bitmap(bitmapdata); bitmapdata.draw(e.target.content); var threshold:uint = 0xF9F8F800; var color:uint = 0x00000000; var maskColor:uint = 0x00FF0000; bitmapdata.threshold(bitmapdata,new Rectangle(0,0,W,H),new Point(0,0),">", threshold, color, maskColor, true); bitmap.smoothing = true; //bitmap.scaleX = bitmap.scaleY = 0.99; // <---- imgHolder.addChild(bitmap); } }

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• Nicely representing a floating-point number in python

  - by dln385

  I want to represent a floating-point number as a string rounded to some number of significant digits, and never using the exponential format. Essentially, I want to display any floating-point number and make sure it “looks nice”. There are several parts to this problem: I need to be able to specify the number of significant digits. The number of significant digits needs to be variable, which can't be done with with the string formatting operator. I need it to be rounded the way a person would expect, not something like 1.999999999999 I've figured out one way of doing this, though it looks like a work-round and it's not quite perfect. (The maximum precision is 15 significant digits.) >>> def f(number, sigfig): return ("%.15f" % (round(number, int(-1 * floor(log10(number)) + (sigfig - 1))))).rstrip("0").rstrip(".") >>> print f(0.1, 1) 0.1 >>> print f(0.0000000000368568, 2) 0.000000000037 >>> print f(756867, 3) 757000 Is there a better way to do this? Why doesn't Python have a built-in function for this?

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• Using ARIMA to model and forecast stock prices using user-friendly stats program

  - by Brian

  Hi people, Can anyone please offer some insight into this for me? I'm coming from a functional magnetic resonance imaging research background where I analyzed a lot of time series data, and I'd like to analyze the time series of stock prices (or returns) by: 1) modeling a successful stock in a particular market sector and then cross-correlating the time series of this historically successful stock with that of other newer stocks to look for significant relationships; 2) model a stock's price time series and use forecasting (e.g., exponential smoothing) to predict future values of it. I'd like to use non-linear modeling methods (ARIMA and ARCH) to do this. Several questions: How often do ARIMA and ARCH modeling methods (given that the individual who implements them does so accurately) actually fit the stock time series data they target, and what is the optimal fit I can expect? Is the extent to which this model fits the data commensurate with the extent to which it predicts this stock time series' future values? Rather than randomly selecting stocks to compare or model, if profit is my goal, what is an efficient approach, if any, to selecting the stocks I'm going to analyze? Which stats program is the most user-friendly for this? Any thoughts on this would be great and would go a long way for me. Thanks, Brian

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• How to make UISlider output nice rounded numbers exponentially?

  - by RickiG

  Hi I am implementing a UISlider a user can manipulate to set a distance. I have never used the CocoaTouch UISlider, but have used other frameworks sliders, usually there is a variable for setting the "step" and other "helper" properties. The documentation for the UISlider deals only with a max and min value, and the output is always a 6 decimal float with a linear relation to the position of the "slider nob". I guess I will have to implement the desired functionality step by step. To the user, the min/max values range from 10 m to 999 Km, I am trying to implement this in an exponential way, that will feel natural to the user. I.e. the user experiences a feeling of control over the values, big or small. Also that the "output" has reasonable values. Values like 10m 200m 2.5km 150 km etc. instead of 1.2342356 m or 108.93837756 km. I would like for the step size to increase by 10m for the first 200m, then maybe by 50m up to 500m, then when passing the 1000 m value, it starts to deal with Kilometers, so then it is step size = 1 km up until 50 km, then maybe 25 km steps etc. Any way I go about this I end up doing a lot of rounding and a lot of calculations wrapped in a forrest of if statements and NSString/Number conversions, each time the user moves the slider just a little. I was hoping someone could lend me a bit of inspiration/math help or make me aware of a more lean approach to solving this problem. My last idea is to populate and array with a 100 string values, then have the slider int value correspond to a string, this is not very flexible, but doable. Thank you in advance for any help given:)

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• Curve fitting: Find a CDF (or any function) that satisfies a list of constraints.

  - by dreeves

  I have some constraints on a CDF in the form of a list of x-values and for each x-value, a pair of y-values that the CDF must lie between. We can represent that as a list of {x,y1,y2} triples such as constraints = {{0, 0, 0}, {1, 0.00311936, 0.00416369}, {2, 0.0847077, 0.109064}, {3, 0.272142, 0.354692}, {4, 0.53198, 0.646113}, {5, 0.623413, 0.743102}, {6, 0.744714, 0.905966}} Graphically that looks like this: And since this is a CDF there's an additional implicit constraint of {Infinity, 1, 1} Ie, the function must never exceed 1. Also, it must be monotone. Now, without making any assumptions about its functional form, we want to find a curve that respects those constraints. For example: (I cheated to get that one: I actually started with a nice log-normal distribution and then generated fake constraints based on it.) One possibility is a straight interpolation through the midpoints of the constraints: mids = ({#1, Mean[{#2,#3}]}&) @@@ constraints f = Interpolation[mids, InterpolationOrder->0] Plotted, f looks like this: That sort of technically satisfies the constraints but it needs smoothing. We can increase the interpolation order but now it violates the implicit constraints (always less than one, and monotone): How can I get a curve that looks as much like the first one above as possible? Note that NonLinearModelFit with a LogNormalDistribution will do the trick in this example but is insufficiently general as sometimes there will sometimes not exist a log-normal distribution satisfying the constraints.

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• movie does not start in full screen in flash video player

  - by jodeci

  We have this legacy code of a flash video player that functions well enough but still has some loose ends I need to tighten up. It can do the basic "switch to full screen and back to normal size" stunts, however with one exception. On the first fresh load of the app, if I switch to full screen mode first, and then click to play the movie, the player would be in full screen, yet the movie itself would remain in it's original size. //trigger if (stage.displayState == StageDisplayState.NORMAL) { stage.addEventListener('fullScreen', procFullScreen); stage.scaleMode = StageScaleMode.NO_SCALE; stage.displayState = StageDisplayState.FULL_SCREEN; //mv:VideoDisplay mv.percentHeight = 100; mv.percentWidth = 100; mv.x = 0; mv.y = 0; } // event handler if (event.fullScreen) { mv.smoothing = true; this.height = stage.height; this.width = stage.width; //videoCanvas:Canvas videoCanvas.height = Application.application.height; videoCanvas.width = Application.application.width; fullScreenViewStack.selectedIndex = 1; } The VideoDisplay object even returns the expected width/height, but the movie just plays in it's original size. If I switch screen sizes during movie playback, then the movie size will shrink or stretch as it should. I'm running out of ideas, any suggestions? Thanks in advance!

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• I need to Loop an a formula with the Offset function until the cell is blank

  - by CEMG

  I need to Loop the formula below until Column "B" which contains dates is empty. I am stuck and I just can't seem to write the VBA Code to do the Loop until there is no more Dates in Column "B". The formula is smoothing out the yields by using those dates that have a yield. I hope anyone would be able to help me. Thanks in advance A B C D 5 Factor Date Yield Input 6 3 May-10 .25 7 1 Jun-10 8 2 Jul-10 9 3 Aug-10 0.2000 10 1 Sep-10 11 2 Oct-10 12 3 Nov-10 0.2418 13 1 Dec-10 14 2 Jan-11 15 3 Feb-11 0.3156 16 1 Mar-11 17 2 Apr-11 . Sub IsNumeric() 'IF(ISNUMBER(C6),C6, If Application.IsNumber(range("c6").Value) Then range("d6").Value = range("c6") 'IF(C6<C5,((OFFSET(C6,2,0)-OFFSET(C6,-1,0))*A6/3+OFFSET(C6,-1,0)), If range("c6").Select < range("c5").Select Then range("d6").Value = range("c6").Offset(2, 0).Select - range("c6").Offset(-1, 0).Select * (range("a6").Select / 3) + range("c6").Offset(-1, 0).Select 'IF(C6<>C7,((OFFSET(C6,1,0)-OFFSET(C6,-2,0))*(A6/3)+OFFSET(C6,-2,0)),""))) If range("c6").Select <> range("c7").Select Then range("d6").Value = (range("c6").Offset(1, 0).Select) - range("c6").Offset(-2, 0).Select * (range("a6").Select / 3) + range("c6").Offset(-2, 0).Select Else range("d6").Value = "" End If End If End If End Sub

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• i integer does not +1 the 1st time

  - by Hwang

  I have a gallery where it will load an image after a previous image is loaded, so every time 'i' will +1 so that it could move to the next image. This code works fine on my other files, but I dunno why it doesn't work for the current file. Normally if I trace 'i' the correct will be 0,1,2,3,4,5,6... etc adding on till the limit, but this files its 'i' repeat the 1st number twice, only it continues to add 0,0,1,2,3,4,5,6...etc The code is completely the same with the other file I'm using, but I don't know why it just doesn't work here. The code does not seems to have any problem. Anyway i can work around this situation? private var i:uint=0; private function loadItem():void { if (i<myXMLList.length()) { loadedPic=myXMLList[i].thumbnails; galleryLoader = new Loader(); galleryLoader.load(new URLRequest(loadedPic)); galleryLoader.contentLoaderInfo.addEventListener(Event.COMPLETE,picLoaded); } else { adjustImage(); } } private function picLoaded(event:Event):void { var bmp=new Bitmap(event.target.content.bitmapData); bmp.smoothing=true; bmpArray.push(bmp); imagesArray[i].addChild(bmp); i++; loadItem(); }

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• Setting pixel values in Nvidia NPP ImageCPU objects?

  - by solvingPuzzles

  In the Nvidia Performance Primitives (NPP) image processing examples in the CUDA SDK distribution, images are typically stored on the CPU as ImageCPU objects, and images are stored on the GPU as ImageNPP objects. boxFilterNPP.cpp is an example from the CUDA SDK that uses these ImageCPU and ImageNPP objects. When using a filter (convolution) function like nppiFilter, it makes sense to define a filter as an ImageCPU object. However, I see no clear way setting the values of an ImageCPU object. npp::ImageCPU_32f_C1 hostKernel(3,3); //allocate space for 3x3 convolution kernel //want to set hostKernel to [-1 0 1; -1 0 1; -1 0 1] hostKernel[0][0] = -1; //this doesn't compile hostKernel(0,0) = -1; //this doesn't compile hostKernel.at(0,0) = -1; //this doesn't compile How can I manually put values into an ImageCPU object? Notes: I didn't actually use nppiFilter in the code snippet; I'm just mentioning nppiFilter as a motivating example for writing values into an ImageCPU object. The boxFilterNPP.cpp example doesn't involve writing directly to an ImageCPU object, because nppiFilterBox is a special case of nppiFilter that uses a built-in gaussian smoothing filter (probably something like [1 1 1; 1 1 1; 1 1 1]).

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• What would cause my SendMail server not to acknowledge receiving a TCP Sequence?

  - by Mike B

  My TCP/IP Stack knowledge is a little rusty so please bear with me.... I have a CentOS 5.7 server with SendMail and am having seeing intermittent timeout issues sending email (particularly larger email) to other remote domains. It doesn't happen with all attachments or recipient domains. Just some. After some extended troubleshooting, I think I've narrowed it down to TCP Sequences not being acknowledged. Here's a breakdown of the TCP session from a packet capture I collected directly on my MTA (fooMTA): Packet 1 - 11: Standard TCP handshake followed by initial SMTP conversation. No errors. Packet #12 Recipient MTA: TCP sequence 231. Ack 91. Packet #13 FooMTA: TCP sequence 91. Ack 305. Packet #14 FooMTA: TCP sequence 1115. Ack 305. Packet #15 Recipient MTA: TCP sequence 305. Ack 2495. Packet #16 FooMTA: TCP sequence 2495. Ack 305. Packet #17 FooMTA: TCP sequence 5255. Ack 305. Packet #18: Recipient MTA: TCP sequence 305. Ack 5255. Packet #19: FooMTA: TCP sequence 6635. Ack 305. Packet #20: FooMTA: TCP sequence 8015. Ack 305. Packet #21: Recipient MTA: TCP Sequence 305. Ack 8015. Packet #22: FooMTA: TCP Sequence 10775. Ack 305. Packet #23: FooMTA: TCP Sequence 13535. Ack 305. Packet #24: Recipient MTA: TCP sequence 305. Ack 10775 Packet #25: FooMTA: TCP Sequence 14915. Ack 305 It keeps going like this with my server still thinking it hasn’t received sequence 305… in response the remote side eventually retransmits its prior data thinking that it never arrived. Eventually the gap gets so large that no new data is sent and the remote MTA keeps retransmitting old stuff. This contributes to an exponential backoff and eventually the remote side gives up. What’s strange to me is that I see the “missing” TCP sequence (305 in this case) arriving back to my server (via a packet capture collected directly from fooMTA) So I don’t get why my server keeps asking for it. Could this be firewall related? What would be the next step in troubleshooting?

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• Big Data – What is Big Data – 3 Vs of Big Data – Volume, Velocity and Variety – Day 2 of 21

  - by Pinal Dave

  Data is forever. Think about it – it is indeed true. Are you using any application as it is which was built 10 years ago? Are you using any piece of hardware which was built 10 years ago? The answer is most certainly No. However, if I ask you – are you using any data which were captured 50 years ago, the answer is most certainly Yes. For example, look at the history of our nation. I am from India and we have documented history which goes back as over 1000s of year. Well, just look at our birthday data – atleast we are using it till today. Data never gets old and it is going to stay there forever.  Application which interprets and analysis data got changed but the data remained in its purest format in most cases. As organizations have grown the data associated with them also grew exponentially and today there are lots of complexity to their data. Most of the big organizations have data in multiple applications and in different formats. The data is also spread out so much that it is hard to categorize with a single algorithm or logic. The mobile revolution which we are experimenting right now has completely changed how we capture the data and build intelligent systems.  Big organizations are indeed facing challenges to keep all the data on a platform which give them a  single consistent view of their data. This unique challenge to make sense of all the data coming in from different sources and deriving the useful actionable information out of is the revolution Big Data world is facing. Defining Big Data The 3Vs that define Big Data are Variety, Velocity and Volume. Volume We currently see the exponential growth in the data storage as the data is now more than text data. We can find data in the format of videos, musics and large images on our social media channels. It is very common to have Terabytes and Petabytes of the storage system for enterprises. As the database grows the applications and architecture built to support the data needs to be reevaluated quite often. Sometimes the same data is re-evaluated with multiple angles and even though the original data is the same the new found intelligence creates explosion of the data. The big volume indeed represents Big Data. Velocity The data growth and social media explosion have changed how we look at the data. There was a time when we used to believe that data of yesterday is recent. The matter of the fact newspapers is still following that logic. However, news channels and radios have changed how fast we receive the news. Today, people reply on social media to update them with the latest happening. On social media sometimes a few seconds old messages (a tweet, status updates etc.) is not something interests users. They often discard old messages and pay attention to recent updates. The data movement is now almost real time and the update window has reduced to fractions of the seconds. This high velocity data represent Big Data. Variety Data can be stored in multiple format. For example database, excel, csv, access or for the matter of the fact, it can be stored in a simple text file. Sometimes the data is not even in the traditional format as we assume, it may be in the form of video, SMS, pdf or something we might have not thought about it. It is the need of the organization to arrange it and make it meaningful. It will be easy to do so if we have data in the same format, however it is not the case most of the time. The real world have data in many different formats and that is the challenge we need to overcome with the Big Data. This variety of the data represent  represent Big Data. Big Data in Simple Words Big Data is not just about lots of data, it is actually a concept providing an opportunity to find new insight into your existing data as well guidelines to capture and analysis your future data. It makes any business more agile and robust so it can adapt and overcome business challenges. Tomorrow In tomorrow’s blog post we will try to answer discuss Evolution of Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Increasing efficiency of N-Body gravity simulation

  - by Postman

  I'm making a space exploration type game, it will have many planets and other objects that will all have realistic gravity. I currently have a system in place that works, but if the number of planets goes above 70, the FPS decreases an practically exponential rates. I'm making it in C# and XNA. My guess is that I should be able to do gravity calculations between 100 objects without this kind of strain, so clearly my method is not as efficient as it should be. I have two files, Gravity.cs and EntityEngine.cs. Gravity manages JUST the gravity calculations, EntityEngine creates an instance of Gravity and runs it, along with other entity related methods. EntityEngine.cs public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { e.Value.Update(); } gravity.Update(); } (Only relevant piece of code from EntityEngine, self explanatory. When an instance of Gravity is made in entityEngine, it passes itself (this) into it, so that gravity can have access to entityEngine.Entities (a dictionary of all planet objects)) Gravity.cs namespace ExplorationEngine { public class Gravity { private EntityEngine entityEngine; private Vector2 Force; private Vector2 VecForce; private float distance; private float mult; public Gravity(EntityEngine e) { entityEngine = e; } public void Update() { //First loop foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { //Reset the force vector Force = new Vector2(); //Second loop foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { //Make sure the second value is not the current value from the first loop if (e2.Value != e.Value ) { //Find the distance between the two objects. Because Fg = G * ((M1 * M2) / r^2), using Vector2.Distance() and then squaring it //is pointless and inefficient because distance uses a sqrt, squaring the result simple cancels that sqrt. distance = Vector2.DistanceSquared(e2.Value.Position, e.Value.Position); //This makes sure that two planets do not attract eachother if they are touching, completely unnecessary when I add collision, //For now it just makes it so that the planets are not glitchy, performance is not significantly improved by removing this IF if (Math.Sqrt(distance) > (e.Value.Texture.Width / 2 + e2.Value.Texture.Width / 2)) { //Calculate the magnitude of Fg (I'm using my own gravitational constant (G) for the sake of time (I know it's 1 at the moment, but I've been changing it) mult = 1.0f * ((e.Value.Mass * e2.Value.Mass) / distance); //Calculate the direction of the force, simply subtracting the positions and normalizing works, this fixes diagonal vectors //from having a larger value, and basically makes VecForce a direction. VecForce = e2.Value.Position - e.Value.Position; VecForce.Normalize(); //Add the vector for each planet in the second loop to a force var. Force = Vector2.Add(Force, VecForce * mult); //I have tried Force += VecForce * mult, and have not noticed much of an increase in speed. } } } //Add that force to the first loop's planet's position (later on I'll instead add to acceleration, to account for inertia) e.Value.Position += Force; } } } } I have used various tips (about gravity optimizing, not threading) from THIS question (that I made yesterday). I've made this gravity method (Gravity.Update) as efficient as I know how to make it. This O(N^2) algorithm still seems to be eating up all of my CPU power though. Here is a LINK (google drive, go to File download, keep .Exe with the content folder, you will need XNA Framework 4.0 Redist. if you don't already have it) to the current version of my game. Left click makes a planet, right click removes the last planet. Mouse moves the camera, scroll wheel zooms in and out. Watch the FPS and Planet Count to see what I mean about performance issues past 70 planets. (ALL 70 planets must be moving, I've had 100 stationary planets and only 5 or so moving ones while still having 300 fps, the issue arises when 70+ are moving around) After 70 planets are made, performance tanks exponentially. With < 70 planets, I get 330 fps (I have it capped at 300). At 90 planets, the FPS is about 2, more than that and it sticks around at 0 FPS. Strangely enough, when all planets are stationary, the FPS climbs back up to around 300, but as soon as something moves, it goes right back down to what it was, I have no systems in place to make this happen, it just does. I considered multithreading, but that previous question I asked taught me a thing or two, and I see now that that's not a viable option. I've also thought maybe I could do the calculations on my GPU instead, though I don't think it should be necessary. I also do not know how to do this, it is not a simple concept and I want to avoid it unless someone knows a really noob friendly simple way to do it that will work for an n-body gravity calculation. (I have an NVidia gtx 660) Lastly I've considered using a quadtree type system. (Barnes Hut simulation) I've been told (in the previous question) that this is a good method that is commonly used, and it seems logical and straightforward, however the implementation is way over my head and I haven't found a good tutorial for C# yet that explains it in a way I can understand, or uses code I can eventually figure out. So my question is this: How can I make my gravity method more efficient, allowing me to use more than 100 objects (I can render 1000 planets with constant 300+ FPS without gravity calculations), and if I can't do much to improve performance (including some kind of quadtree system), could I use my GPU to do the calculations?

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• Flash -> ByteArray -> AMFPHP -> Invalid Image !??

  - by undefined

  Hi, Im loading images into Flash and using JPGEncoder to encode the image to a ByteArray and send this to AMF PHP which writes out the bytearray to a file. This all appears to work correctly and I can download the resulting file in Photoshop CS4 absolutely fine. When i try to open it from the desktop or open it back in Flash it doesnt work... Picasa my default image browser says "Invalid" Here is the code i use to write the bytearray to a file - $jpg = $GLOBALS["HTTP_RAW_POST_DATA"]; file_put_contents($filename, $jpg); That's it ... I use the NetConnection class to connect and call the service, do I need to say Im sending jpg data? I assumed that JPGEncoder took care of that. How can I validate the bytearray before writing the file? Do I need to set MIME type or something .. excuse the slightly noob questions, a little knowledge can be a dangerous thing. Thanks --------------------------------------- PART II ------------------------------------------ Here is some code - 1) load the image into Flash player item.load(); function _onImageDataLoaded(evt:Event):void { var tmpFileRef:FileReference=FileReference(evt.target); image_loader=new Loader ; image_loader.contentLoaderInfo.addEventListener(Event.COMPLETE, _onImageLoaded); image_loader.loadBytes(tmpFileRef.data); } function _onImageLoaded(evt:Event):void { bitmap=Bitmap(evt.target.content); bitmap.smoothing=true; if (bitmap.width>MAX_WIDTH||bitmap.height>MAX_HEIGHT) { resizeBitmap(bitmap); } uploadResizedImage(bitmap); } function resizeBitmap(target:Bitmap):void { if (target.height>target.width) { target.width=MAX_WIDTH; target.scaleY=target.scaleX; } else if (target.width >= target.height) { target.height=MAX_HEIGHT; target.scaleX=target.scaleY; } } function uploadResizedImage(target:Bitmap):void { var _bmd:BitmapData=new BitmapData(target.width,target.height); _bmd.draw(target, new Matrix(target.scaleX, 0, 0, target.scaleY)); var encoded_jpg:JPGEncoder=new JPGEncoder(90); var jpg_binary:ByteArray=encoded_jpg.encode(_bmd); _uploadService=new NetConnection(); _uploadService.objectEncoding=ObjectEncoding.AMF3 _uploadService.connect("http://.../amfphp/gateway.php"); _uploadService.call("UploadService.receiveByteArray",new Responder(success, error), jpg_binary, currentImageFilename); } Many thanks for you help

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• SilverLight 3 Beginner question: Scroll with mousewheel and zoom image with panning

  - by JP Hellemons

  Hello, I would like to make a small silverlight app which displays one fairly large image which can be zoomed in by scrolling the mouse and then panned with the mouse. it's similar to the function in google maps and i do not want to use deepzoom. here is what i have at the moment. please keep in mind that this is my first silverlight app: this app is just for me to see it's a good way to build in a website. so it's a demo app and therefor has bad variable names. the initial image is 1800px width. private void sc_MouseWheel(object sender, MouseWheelEventArgs e) { var st = (ScaleTransform)plaatje.RenderTransform; double zoom = e.Delta > 0 ? .1 : -.1; st.ScaleX += zoom; st.ScaleY += zoom; } this works, but could use some smoothing and it's positioned top left and not centered. the panning is like this: found it @ http://stackoverflow.com/questions/741956/wpf-pan-zoom-image and converted it to this below to work in silverlight Point start; Point origin; bool captured = false; private void plaatje_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { plaatje.CaptureMouse(); captured = true; var tt = (TranslateTransform)((TransformGroup)plaatje.RenderTransform) .Children.First(tr => tr is TranslateTransform); start = e.GetPosition(canvasje); origin = new Point(tt.X, tt.Y); } private void plaatje_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) { plaatje.ReleaseMouseCapture(); captured = false; } private void plaatje_MouseMove(object sender, MouseEventArgs e) { if (!captured) return; var tt = (TranslateTransform)((TransformGroup)plaatje.RenderTransform).Children.First(tr => tr is TranslateTransform); double xVerschuiving = start.X - e.GetPosition(canvasje).X; double yVerschuiving = start.Y - e.GetPosition(canvasje).Y; tt.X = origin.X - xVerschuiving; tt.Y = origin.Y - yVerschuiving; } so the scaling isn't smooth and the panning isn't working, because when i click it, the image disappears. thanks in advanced!

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• Error using `loess.smooth` but not `loess` or `lowess`

  - by Sandy

  I need to smooth some simulated data, but occasionally run into problems when the simulated ordinates to be smoothed are mostly the same value. Here is a small reproducible example of the simplest case. > x <- 0:50 > y <- rep(0,51) > loess.smooth(x,y) Error in simpleLoess(y, x, w, span, degree, FALSE, FALSE, normalize = FALSE, : NA/NaN/Inf in foreign function call (arg 1) loess(y~x), lowess(x,y), and their analogue in MATLAB produce the expected results without error on this example. I am using loess.smooth here because I need the estimates evaluated at a set number of points. According to the documentation, I believe loess.smooth and loess are using the same estimation functions, but the former is an "auxiliary function" to handle the evaluation points. The error seems to come from a C function: > traceback() 3: .C(R_loess_raw, as.double(pseudovalues), as.double(x), as.double(weights), as.double(weights), as.integer(D), as.integer(N), as.double(span), as.integer(degree), as.integer(nonparametric), as.integer(order.drop.sqr), as.integer(sum.drop.sqr), as.double(span * cell), as.character(surf.stat), temp = double(N), parameter = integer(7), a = integer(max.kd), xi = double(max.kd), vert = double(2 * D), vval = double((D + 1) * max.kd), diagonal = double(N), trL = double(1), delta1 = double(1), delta2 = double(1), as.integer(0L)) 2: simpleLoess(y, x, w, span, degree, FALSE, FALSE, normalize = FALSE, "none", "interpolate", control$cell, iterations, control$trace.hat) 1: loess.smooth(x, y) loess also calls simpleLoess, but with what appears to be different arguments. Of course, if you vary enough of the y values to be nonzero, loess.smooth runs without error, but I need the program to run in even the most extreme case. Hopefully, someone can help me with one and/or all of the following: Understand why only loess.smooth, and not the other functions, produces this error and find a solution for this problem. Find a work-around using loess but still evaluating the estimate at a specified number of points that can differ from the vector x. For example, I might want to use only x <- seq(0,50,10) in the smoothing, but evaluate the estimate at x <- 0:50. As far as I know, using predict with a new data frame will not properly handle this situation, but please let me know if I am missing something there. Handle the error in a way that doesn't stop the program from moving onto the next simulated data set. Thanks in advance for any help on this problem.

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• decorator pattern

  - by vbNewbie

  I have a program that converts currency using a specific design pattern. I now need to take my converted result and using the decorator pattern allow the result to be converted to 3 different formats: 1 - exponential notation, rounded to 2 decimal points. using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; namespace Converter { public partial class Form1 : Form { // Setup Chain of Responsibility Handler h1 = new USDHandler(); Handler h2 = new CADHandler(); Handler h3 = new AUDHandler(); public string reqCurName; public int reqAmt; public string results; public string requestID; public Form1() { InitializeComponent(); h1.SetSuccessor(h2); h2.SetSuccessor(h3); } // "Handler" private void button1_Click_1(object sender, EventArgs e) { reqCurName = txtInput.Text; reqAmt = Convert.ToInt32(txtAmt.Text.ToString()); results = h1.HandleRequest(reqCurName, reqAmt); if (results != "") { lblResult.Text = results; lblResult.Visible = true; } } abstract class Handler { protected Handler successor; public string retrn; public void SetSuccessor(Handler successor) { this.successor = successor; } public abstract string HandleRequest(string requestID, int reqAmt); } // "USD Handler" class USDHandler : Handler { public override string HandleRequest(string requestID, int reqAmt) { if (requestID == "USD") { retrn = "Request handled by " + this.GetType().Name + " \nConversion from Euro to USD is " + reqAmt/0.630479; return (retrn); } else if (successor != null) { retrn = successor.HandleRequest(requestID, reqAmt); } return (retrn); } } // "CAD Handler" class CADHandler : Handler { public override string HandleRequest(string requestID, int reqAmt) { if (requestID == "CAD") { retrn = "Request handled by " + this.GetType().Name + " \nConversion from Euro to CAD is " + reqAmt /0.617971; return (retrn); } else if (successor != null) { retrn = successor.HandleRequest(requestID, reqAmt); } return (retrn); } } // "AUD Handler" class AUDHandler : Handler { public override string HandleRequest(string requestID, int reqAmt) { if (requestID == "AUD") { requestID = "Request handled by " + this.GetType().Name + " \nConversion from Euro to AUD is " + reqAmt / 0.585386; return (requestID); } else if (successor != null) { retrn = successor.HandleRequest(requestID, reqAmt); } return (requestID); } } } }

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• save button error in AS project

  - by Rajeev

  Whats wrong with the following code,There is an error at saveButton.visible = false; discardButton.visible = false; package { import flash.display.Sprite; import flash.media.Camera; import flash.media.Video; import flash.display.BitmapData; import flash.display.Bitmap; import flash.events.MouseEvent; import flash.net.FileReference; import flash.utils.ByteArray; import com.adobe.images.JPGEncoder; public class caml extends Sprite { private var camera:Camera = Camera.getCamera(); private var video:Video = new Video(); private var bmd:BitmapData = new BitmapData(320,240); private var bmp:Bitmap; private var fileReference:FileReference = new FileReference(); private var byteArray:ByteArray; private var jpg:JPGEncoder = new JPGEncoder(); public function caml() { saveButton.visible = false; discardButton.visible = false; saveButton.addEventListener(MouseEvent.MOUSE_UP, saveImage); discardButton.addEventListener(MouseEvent.MOUSE_UP, discard); capture.addEventListener(MouseEvent.MOUSE_UP, captureImage); if (camera != null) { video.smoothing = true; video.attachCamera(camera); video.x = 140; video.y = 40; addChild(video); } else { trace("No Camera Detected"); } } private function captureImage(e:MouseEvent):void { bmd.draw(video); bmp = new Bitmap(bmd); bmp.x = 140; bmp.y = 40; addChild(bmp); capture.visible = false; saveButton.visible = true; discardButton.visible = true; } private function saveImage(e:MouseEvent):void { byteArray = jpg.encode(bmd); fileReference.save(byteArray, "Image.jpg"); removeChild(bmp); saveButton.visible = false; discardButton.visible = false; capture.visible = true; } private function discard(e:MouseEvent):void { removeChild(bmp); saveButton.visible = false; discardButton.visible = false; capture.visible = true; } } }

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• Upload picture directly to the server

  - by Rajeev

  In the following link http://www.tuttoaster.com/create-a-camera-application-in-flash-using-actionscript-3/ how to make the picture upload directly to the server after taking a picture from webcam package { import flash.display.Sprite; import flash.media.Camera; import flash.media.Video; import flash.display.BitmapData; import flash.display.Bitmap; import flash.events.MouseEvent; import flash.net.FileReference; import flash.utils.ByteArray; import com.adobe.images.JPGEncoder; public class caml extends Sprite { private var camera:Camera = Camera.getCamera(); private var video:Video = new Video(); private var bmd:BitmapData = new BitmapData(320,240); private var bmp:Bitmap; private var fileReference:FileReference = new FileReference(); private var byteArray:ByteArray; private var jpg:JPGEncoder = new JPGEncoder(); public function caml() { saveButton.visible = false; discardButton.visible = false; saveButton.addEventListener(MouseEvent.MOUSE_UP, saveImage); discardButton.addEventListener(MouseEvent.MOUSE_UP, discard); capture.addEventListener(MouseEvent.MOUSE_UP, captureImage); if (camera != null) { video.smoothing = true; video.attachCamera(camera); video.x = 140; video.y = 40; addChild(video); } else { trace("No Camera Detected"); } } private function captureImage(e:MouseEvent):void { bmd.draw(video); bmp = new Bitmap(bmd); bmp.x = 140; bmp.y = 40; addChild(bmp); capture.visible = false; saveButton.visible = true; discardButton.visible = true; } private function saveImage(e:MouseEvent):void { byteArray = jpg.encode(bmd); fileReference.save(byteArray, "Image.jpg"); removeChild(bmp); saveButton.visible = false; discardButton.visible = false; capture.visible = true; } private function discard(e:MouseEvent):void { removeChild(bmp); saveButton.visible = false; discardButton.visible = false; capture.visible = true; } } }

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• Getting Frequency Components with FFT

  - by ruhig brauner

  so I was able to solv my last problem but i stubmled upon the next already. So I want to make a simple spectrogram but in oder to do so I want to understand how FFT-libaries work and what they actually calculate and return. (FFT and Signal Processing is the number 1 topic I will get into as soon as I have time but right now, I only have time for some programming exercises in the evening. ;) ) Here I just summarized the most important parts: int framesPerSecond; int samplesPerSecond; int samplesPerCycle; // right now i want to refresh the spectogram every DoubleFFT_1D fft; WAVReader audioIn; double audioL[], audioR[]; double fftL[], fftR[]; ..... framesPerSecond = 30; audioIn= new WAVReader("Strobe.wav"); int samplesPerSecond = (int)audioIn.GetSampleRate(); samplesPerCycle = (int)(audioIn.GetSampleRate()/framesPerSecond); audioL = new double[samplesPerCycle*2]; audioR = new double[samplesPerCycle*2]; fftL = new double[samplesPerCycle]; fftR = new double[samplesPerCycle]; for(int i = 0; i < samplesPerCycle; i++) { // don't even know why,... fftL[i] = 0; fftR[i] = 0; } fft = new DoubleFFT_1D(samplesPerCycle); ..... for(int i = 0; i < samplesPerCycle; i++) { audioIn.GetStereoSamples(temp); audioL[i]=temp[0]; audioR[i]=temp[1]; } fft.realForwardFull(audioL); //still stereo fft.realForwardFull(audioR); System.out.println("Check"); for(int i = 0; i < samplesPerCycle; i++) { //storing the magnitude in the fftL/R arrays fftL[i] = Math.sqrt(audioL[2*i]*audioL[2*i] + audioL[2*i+1]*audioL[2*i+1]); fftR[i] = Math.sqrt(audioR[2*i]*audioR[2*i] + audioR[2*i+1]*audioR[2*i+1]); } So the question is, if I want to know, what frequencys are in the sampled signal, how do I calculate them? (When I want to print the fftL / fftR arrays, I get some exponential formes at both ends of the array.) Thx :)

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• MIX 2010 Covert Operations Day 2 Silverlight + Windows 7 Phone

  - by GeekAgilistMercenary

  Left the Circus Circus and headed to the geek circus at Mandalay Bay.  Got in, got some breakfast, met a few more people and headed to the keynote. Upon arriving the crew I was hanging with at the event; Erik Mork, Beth Murray, and Brian Henderson and I were entertained with several other thousand geeks by the wicked yo-yoing. The first video demo of something was of Bing Maps and various aspects of Microsoft Research integrated together.  Namely the pictures, put in place, on real 3d element maps of various environments. Silverlight Scott Guthrie, as one would guess, kicked off the keynote.  His first point was that user experience has become a priority at Microsoft.  This can be seen by any observant soul with the release and push of Expression, Silverlight, and the other tools.  This is even more apparent when one takes note of Microsoft bringing in people that can actually do good design and putting them at the forefront. The next thing Scott brought up was a few key points about Silverlight.  Currently Silverlight is a little over 2 years old and has achieved a pretty solid 60% penetration.  Silverlight has all sorts of capabilities that have been developed and are now provided as open source including;  ad injection, smoothing, playback editing, and more.  Another thing he showed, which really struck me as awesome being in the analytics space, was the Olympics and a quick glimpse of the ad statistics, viewer experience, video playback performance, audience trends, and overall viewer participation.  All of it rendered in Silverlight in beautiful detail. The key piece of Scott's various points were all punctuated with the fact that all of this code is available as open source.  Not only is Microsoft really delving into this design element of things, they're getting involved in the right ways. One of the last points I'll bring up about Silverlight 4 is the ability to have HD video on a monitor, and an entirely different activity being done on the other monitor, effectively making Silverlight the only RIA framework that supports multi-monitor support.  Overall, Silverlight is continuing to impress – providing superior capabilities tit-for-tat with the competition. Windows 7 Phone The Windows 7 Phone has 3 primary buttons (yes, more than the iPhone, don't let your mind explode!!).  Start, Search, and Back control all of the needed functionality of the phone.  At the same time, of course, there is the multi-touch, touch, and other interactive abilities of the interface.  The intent, once start is pressed is to have all the information that a phone owner wants displayed immediately.  Avoiding the scrolling through pages of apps or rolling a ball to get through multitudes of other non-interactive phone interfaces.  The Windows 7 Phone simply has the data right in front of you, basically a phone dashboard.  From there it is easy to dive into the interactive areas of the phone. Each area of the interface of the phone is broken into hubs.  These hubs include applications, data, and other things based on a relative basis.  This basis being determined by the user.  These applications interact on many other levels, and form a kind of relationship between each other adding more and more meta-data to the phone user, their interactions between the applications, and of course the social element of their interactions on the phone.  This makes this phone a practical must have for a marketer involved in social media.  The level of wired together interaction is massive, and of course, if you've seen Office Outlook 2010 you know that the power that is pulled into the phone by being tied to Outlook is massive. Joe Belfiore also showed several UI & specifically UX elements of the phone interface that allows paging to be instinctual by simple clipped items, flipping page to page, and other excellent user experience advances for phone devices.  Belfiore's also showed how his people hub had a massive list of people, with pictures, all from various different social networks and other associated relations.  The rendering, speed, and viewing of these people's, their pictures, their social network information, and other characteristics was smooth and in some situations unbelievably rendered.  This demo showed some of the great power of the beta phone, which isn't even as powerful as the planned end device. Joe finished up by jumping into the music, videos, and other media with the Zune Component of the Windows 7 Mobile Phone.  This was all good stuff, but I'll get to what really sold me on the media element in a moment. When Joe was done, Scott Guthrie stepped back up to walk through building a Windows 7 Mobile Phone.  This is were I have to give serious props.  He built this application, in Visual Studio 2010, in front of 2000+ people.  That was cool, but what really was amazing that he build the application in about 2 minutes.  The IDE, side by side design that is standard in Visual Studio is light years ahead of x-Code or any of the iPhone IDEs.  The Windows 7 Mobile System, if it can get market penetration, poses a technologically superior development and phone platform over anything on the market right now.  The biggest problem with the phone, is it just isn't available yet.  I personally can't wait for a chance to build some apps for the new Windows Phone. Netflix, I May Start Up an Account Again! When I get my Windows 7 Phone device, I am absolutely getting a Netflix account again.  The Vertigo crew, as I wrote on Twitter "#MIX10 Props @seesharp on @netflix demo", displayed an application on the phone for Netflix that actually ran HD Video of Rescue Me (with Dennis Leary).  The video played back smooth as it would on a dedicated computer, I was instantly sold.  So this didn't actually sell me on the phone, because I'm already sold, but it did sell me whole heartedly on the media capabilities of the pending phone. Anyway, I try not to do this but I may double post today.  Lunch is over and I'm off to another session very near and dear to the heart of my occupation, Analytics Tracking.  Stay tuned and I should have that post up by the end of the day. Original Post – Check out my other blog for even more technical ramblings and reads.

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• DTracing TCP congestion control

  - by user12820842

  In a previous post, I showed how we can use DTrace to probe TCP receive and send window events. TCP receive and send windows are in effect both about flow-controlling how much data can be received - the receive window reflects how much data the local TCP is prepared to receive, while the send window simply reflects the size of the receive window of the peer TCP. Both then represent flow control as imposed by the receiver. However, consider that without the sender imposing flow control, and a slow link to a peer, TCP will simply fill up it's window with sent segments. Dealing with multiple TCP implementations filling their peer TCP's receive windows in this manner, busy intermediate routers may drop some of these segments, leading to timeout and retransmission, which may again lead to drops. This is termed congestion, and TCP has multiple congestion control strategies. We can see that in this example, we need to have some way of adjusting how much data we send depending on how quickly we receive acknowledgement - if we get ACKs quickly, we can safely send more segments, but if acknowledgements come slowly, we should proceed with more caution. More generally, we need to implement flow control on the send side also. Slow Start and Congestion Avoidance From RFC2581, let's examine the relevant variables: "The congestion window (cwnd) is a sender-side limit on the amount of data the sender can transmit into the network before receiving an acknowledgment (ACK). Another state variable, the slow start threshold (ssthresh), is used to determine whether the slow start or congestion avoidance algorithm is used to control data transmission" Slow start is used to probe the network's ability to handle transmission bursts both when a connection is first created and when retransmission timers fire. The latter case is important, as the fact that we have effectively lost TCP data acts as a motivator for re-probing how much data the network can handle from the sending TCP. The congestion window (cwnd) is initialized to a relatively small value, generally a low multiple of the sending maximum segment size. When slow start kicks in, we will only send that number of bytes before waiting for acknowledgement. When acknowledgements are received, the congestion window is increased in size until cwnd reaches the slow start threshold ssthresh value. For most congestion control algorithms the window increases exponentially under slow start, assuming we receive acknowledgements. We send 1 segment, receive an ACK, increase the cwnd by 1 MSS to 2*MSS, send 2 segments, receive 2 ACKs, increase the cwnd by 2*MSS to 4*MSS, send 4 segments etc. When the congestion window exceeds the slow start threshold, congestion avoidance is used instead of slow start. During congestion avoidance, the congestion window is generally updated by one MSS for each round-trip-time as opposed to each ACK, and so cwnd growth is linear instead of exponential (we may receive multiple ACKs within a single RTT). This continues until congestion is detected. If a retransmit timer fires, congestion is assumed and the ssthresh value is reset. It is reset to a fraction of the number of bytes outstanding (unacknowledged) in the network. At the same time the congestion window is reset to a single max segment size. Thus, we initiate slow start until we start receiving acknowledgements again, at which point we can eventually flip over to congestion avoidance when cwnd ssthresh. Congestion control algorithms differ most in how they handle the other indication of congestion - duplicate ACKs. A duplicate ACK is a strong indication that data has been lost, since they often come from a receiver explicitly asking for a retransmission. In some cases, a duplicate ACK may be generated at the receiver as a result of packets arriving out-of-order, so it is sensible to wait for multiple duplicate ACKs before assuming packet loss rather than out-of-order delivery. This is termed fast retransmit (i.e. retransmit without waiting for the retransmission timer to expire). Note that on Oracle Solaris 11, the congestion control method used can be customized. See here for more details. In general, 3 or more duplicate ACKs indicate packet loss and should trigger fast retransmit . It's best not to revert to slow start in this case, as the fact that the receiver knew it was missing data suggests it has received data with a higher sequence number, so we know traffic is still flowing. Falling back to slow start would be excessive therefore, so fast recovery is used instead. Observing slow start and congestion avoidance The following script counts TCP segments sent when under slow start (cwnd ssthresh). #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::connect-request / start[args[1]-cs_cid] == 0/ { start[args[1]-cs_cid] = 1; } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd tcps_cwnd_ssthresh / { @c["Slow start", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd args[3]-tcps_cwnd_ssthresh / { @c["Congestion avoidance", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } As we can see the script only works on connections initiated since it is started (using the start[] associative array with the connection ID as index to set whether it's a new connection (start[cid] = 1). From there we simply differentiate send events where cwnd ssthresh (congestion avoidance). Here's the output taken when I accessed a YouTube video (where rport is 80) and from an FTP session where I put a large file onto a remote system. # dtrace -s tcp_slow_start.d ^C ALGORITHM RADDR RPORT #SEG Slow start 10.153.125.222 20 6 Slow start 138.3.237.7 80 14 Slow start 10.153.125.222 21 18 Congestion avoidance 10.153.125.222 20 1164 We see that in the case of the YouTube video, slow start was exclusively used. Most of the segments we sent in that case were likely ACKs. Compare this case - where 14 segments were sent using slow start - to the FTP case, where only 6 segments were sent before we switched to congestion avoidance for 1164 segments. In the case of the FTP session, the FTP data on port 20 was predominantly sent with congestion avoidance in operation, while the FTP session relied exclusively on slow start. For the default congestion control algorithm - "newreno" - on Solaris 11, slow start will increase the cwnd by 1 MSS for every acknowledgement received, and by 1 MSS for each RTT in congestion avoidance mode. Different pluggable congestion control algorithms operate slightly differently. For example "highspeed" will update the slow start cwnd by the number of bytes ACKed rather than the MSS. And to finish, here's a neat oneliner to visually display the distribution of congestion window values for all TCP connections to a given remote port using a quantization. In this example, only port 80 is in use and we see the majority of cwnd values for that port are in the 4096-8191 range. # dtrace -n 'tcp:::send { @q[args[4]-tcp_dport] = quantize(args[3]-tcps_cwnd); }' dtrace: description 'tcp:::send ' matched 10 probes ^C 80 value ------------- Distribution ------------- count -1 | 0 0 |@@@@@@ 5 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 0 512 | 0 1024 | 0 2048 |@@@@@@@@@ 8 4096 |@@@@@@@@@@@@@@@@@@@@@@@@@@ 23 8192 | 0

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• A more concise example that illustrates that type inference can be very costly?

  - by mrrusof

  It was brought to my attention that the cost of type inference in a functional language like OCaml can be very high. The claim is that there is a sequence of expressions such that for each expression the length of the corresponding type is exponential on the length of the expression. I devised the sequence below. My question is: do you know of a sequence with more concise expressions that achieves the same types? # fun a -> a;; - : 'a -> 'a = <fun> # fun b a -> b a;; - : ('a -> 'b) -> 'a -> 'b = <fun> # fun c b a -> c b (b a);; - : (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'a -> 'c = <fun> # fun d c b a -> d c b (c b (b a));; - : ((('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'c -> 'd) -> (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'a -> 'd = <fun> # fun e d c b a -> e d c b (d c b (c b (b a)));; - : (((('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'c -> 'd) -> (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'd -> 'e) -> ((('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'c -> 'd) -> (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'a -> 'e = <fun> # fun f e d c b a -> f e d c b (e d c b (d c b (c b (b a))));; - : ((((('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'c -> 'd) -> (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'd -> 'e) -> ((('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'c -> 'd) -> (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'e -> 'f) -> (((('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'c -> 'd) -> (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'd -> 'e) -> ((('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'c -> 'd) -> (('a -> 'b) -> 'b -> 'c) -> ('a -> 'b) -> 'a -> 'f = <fun>

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• Disable antialiasing for a specific GDI device context

  - by Jacob Stanley

  I'm using a third party library to render an image to a GDI DC and I need to ensure that any text is rendered without any smoothing/antialiasing so that I can convert the image to a predefined palette with indexed colors. The third party library i'm using for rendering doesn't support this and just renders text as per the current windows settings for font rendering. They've also said that it's unlikely they'll add the ability to switch anti-aliasing off any time soon. The best work around I've found so far is to call the third party library in this way (error handling and prior settings checks ommitted for brevity): private static void SetFontSmoothing(bool enabled) { int pv = 0; SystemParametersInfo(Spi.SetFontSmoothing, enabled ? 1 : 0, ref pv, Spif.None); } // snip Graphics graphics = Graphics.FromImage(bitmap) IntPtr deviceContext = graphics.GetHdc(); SetFontSmoothing(false); thirdPartyComponent.Render(deviceContext); SetFontSmoothing(true); This obviously has a horrible effect on the operating system, other applications flicker from cleartype enabled to disabled and back every time I render the image. So the question is, does anyone know how I can alter the font rendering settings for a specific DC? Even if I could just make the changes process or thread specific instead of affecting the whole operating system, that would be a big step forward! (That would give me the option of farming this rendering out to a separate process- the results are written to disk after rendering anyway) EDIT: I'd like to add that I don't mind if the solution is more complex than just a few API calls. I'd even be happy with a solution that involved hooking system dlls if it was only about a days work. EDIT: Background Information The third-party library renders using a palette of about 70 colors. After the image (which is actually a map tile) is rendered to the DC, I convert each pixel from it's 32-bit color back to it's palette index and store the result as an 8bpp greyscale image. This is uploaded to the video card as a texture. During rendering, I re-apply the palette (also stored as a texture) with a pixel shader executing on the video card. This allows me to switch and fade between different palettes instantaneously instead of needing to regenerate all the required tiles. It takes between 10-60 seconds to generate and upload all the tiles for a typical view of the world. EDIT: Renamed GraphicsDevice to Graphics The class GraphicsDevice in the previous version of this question is actually System.Drawing.Graphics. I had renamed it (using GraphicsDevice = ...) because the code in question is in the namespace MyCompany.Graphics and the compiler wasn't able resolve it properly. EDIT: Success! I even managed to port the PatchIat function below to C# with the help of Marshal.GetFunctionPointerForDelegate. The .NET interop team really did a fantastic job! I'm now using the following syntax, where Patch is an extension method on System.Diagnostics.ProcessModule: module.Patch( "Gdi32.dll", "CreateFontIndirectA", (CreateFontIndirectA original) => font => { font->lfQuality = NONANTIALIASED_QUALITY; return original(font); }); private unsafe delegate IntPtr CreateFontIndirectA(LOGFONTA* lplf); private const int NONANTIALIASED_QUALITY = 3; [StructLayout(LayoutKind.Sequential)] private struct LOGFONTA { public int lfHeight; public int lfWidth; public int lfEscapement; public int lfOrientation; public int lfWeight; public byte lfItalic; public byte lfUnderline; public byte lfStrikeOut; public byte lfCharSet; public byte lfOutPrecision; public byte lfClipPrecision; public byte lfQuality; public byte lfPitchAndFamily; public unsafe fixed sbyte lfFaceName [32]; }

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• JavaScript Optimisation

  - by Jayie

  I am using JavaScript to work out all the combinations of badminton doubles matches from a given list of players. Each player teams up with everyone else. EG. If I have the following players a, b, c & d. Their combinations can be: a & b V c & d a & c V b & d a & d V b & c I am using the code below, which I wrote to do the job, but it's a little inefficient. It loops through the PLAYERS array 4 times finding every single combination (including impossible ones). It then sorts the game out into alphabetical order and stores it in the GAMES array if it doesn't already exist. I can then use the first half of the GAMES array to list all game combinations. The trouble is if I have any more than 8 players it runs really slowly because the combination growth is exponential. Does anyone know a better way or algorithm I could use? The more I think about it the more my brain hurts! var PLAYERS = ["a", "b", "c", "d", "e", "f", "g"]; var GAMES = []; var p1, p2, p3, p4, i1, i2, i3, i4, entry, found, i; var pos = 0; var TEAM1 = []; var TEAM2 = []; // loop through players 4 times to get all combinations for (i1 = 0; i1 < PLAYERS.length; i1++) { p1 = PLAYERS[i1]; for (i2 = 0; i2 < PLAYERS.length; i2++) { p2 = PLAYERS[i2]; for (i3 = 0; i3 < PLAYERS.length; i3++) { p3 = PLAYERS[i3]; for (i4 = 0; i4 < PLAYERS.length; i4++) { p4 = PLAYERS[i4]; if ((p1 != p2 && p1 != p3 && p1 != p4) && (p2 != p1 && p2 != p3 && p2 != p4) && (p3 != p1 && p3 != p2 && p3 != p4) && (p4 != p1 && p4 != p2 && p4 != p3)) { // sort teams into alphabetical order (so we can compare them easily later) TEAM1[0] = p1; TEAM1[1] = p2; TEAM2[0] = p3; TEAM2[1] = p4; TEAM1.sort(); TEAM2.sort(); // work out the game and search the array to see if it already exists entry = TEAM1[0] + " & " + TEAM1[1] + " v " + TEAM2[0] + " & " + TEAM2[1]; found = false; for (i=0; i < GAMES.length; i++) { if (entry == GAMES[i]) found = true; } // if the game is unique then store it if (!found) { GAMES[pos] = entry; document.write((pos+1) + ": " + GAMES[pos] + "<br>"); pos++; } } } } } } Thanks in advance. Jason.

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