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  • How do I create an OpenCV image from a PIL image?

    - by scrible
    I want to do some image processing with OpenCV (in Python), but I have to start with a PIL Image object, so I can't use the cvLoadImage() call, since that takes a filename. This recipe (adapted from http://opencv.willowgarage.com/wiki/PythonInterface) does not work because cvSetData complains argument 2 of type 'void *' . Any ideas? from opencv.cv import * from PIL import Image pi = Image.open('foo.png') # PIL image ci = cvCreateImage(pi.size, IPL_DEPTH_8U, 1) # OpenCV image data = pi.tostring() cvSetData(ci, data, len(data)) I think the last argument to the cvSetData is wrong too, but I am not sure what it should be.

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  • C lang. -- Error: Segmentaion fault

    - by user233542
    I don't understand why this would give me a seg fault. Any ideas? this is the function that returns the signal to stop the program: (below is the other function that is called within this) double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } double shoot(double Sol[N],double A,double c) { int i,j; /Initial Conditions/ for (i=0;i for (i=buff+2;i return Sol[i-1]; } buff, l, N are defined using a #deine statement. l = 401, buff = 50, N = 2000 Thanks

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  • C# Abort()ing threads on exit for a Form

    - by Gio Borje
    So far I have this code run when the X button is clicked, but I'm not sure if this is the correct way to terminate threads on a form on exit. Type t = this.GetType(); foreach (PropertyInfo pi in t.GetProperties()) { if (pi.GetType() == typeof(Thread)) { MethodInfo mi = pi.GetType().GetMethod("Abort"); mi.Invoke(null, new object[] {}); } } I keep getting this error: "An attempt has been made to free an RCW that is in use. The RCW is in use on the active thread or another thread. Attempting to free an in-use RCW can cause corruption or data loss."

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  • Optimizing MySQL statement with lot of count(row) an sum(row+row2)...

    - by Zombies
    I need to use InnoDB storage engine on a table with about 1mil or so records in it at any given time. It has records being inserted to it at a very fast rate, which are then dropped within a few days, maybe a week. The ping table has about a million rows, whereas the website table only about 10,000. My statement is this: select url from website ws, ping pi where ws.idproxy = pi.idproxy and pi.entrytime > curdate() - 3 and contentping+tcpping is not null group by url having sum(contentping+tcpping)/(count(*)-count(errortype)) < 500 and count(*) > 3 and count(errortype)/count(*) < .15 order by sum(contentping+tcpping)/(count(*)-count(errortype)) asc; I added an index on entrytime, yet no dice. Can anyone throw me a bone as to what I should consider to look into for basic optimization of this query. The result set is only like 200 rows, so I'm not getting killed there.

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  • Unwanted automated creation of new instances of an activity class

    - by Marko
    I have an activity (called Sender) with the most basic UI, only a button that sends a message when clicked. In the onClickListener I only call this method: private void sendSMS(String msg) { PendingIntent pi = PendingIntent.getActivity(this, 0, new Intent(this, Sender.class), 0); PendingIntent pi = PendingIntent.getActivity(this, 0, myIntent, 0); SmsManager sms = SmsManager.getDefault(); sms.sendTextMessage("1477", null, msg, pi, null); } This works ok, the message is sent but every time a message is sent a new instance of Sender is started on top of the other. If I call sendSMS method three times, three new instances are started. I'm quite new to android so I need some help with this, I only want the same Sender to be on all the time

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  • How to extract object reference from property access lamda

    - by Jim C
    Here's a follow-up question to http://stackoverflow.com/questions/2820660/get-name-of-property-as-a-string. Given a method Foo (error checking omitted for brevity): // Example usage: Foo(() => SomeClass.SomeProperty) // Example usage: Foo(() => someObject.SomeProperty) void Foo(Expression<Func<T>> propertyLambda) { var me = propertyLambda.Body as MemberExpression; var pi = me.Member as PropertyInfo; bool propertyIsStatic = pi.GetGetMethod().IsStatic; object owner = propertyIsStatic ? me.Member.DeclaringType : ???; ... // Execute property access object value = pi.GetValue(owner, null); } I've got the static property case working but don't know how to get a reference to someObject in the instance property case. Thanks in advance.

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  • Makefile: expand dependencies

    - by Danyel
    First off, the title is very generic because there are just tons of ways of how to possibly solve this. However, I'm looking for a clean and neat way. Situation: I have two equal object files foo.o and foo-pi.o, the latter of which is position-independent (compiled with -fPIC). Both depend on foo.h and bar.h. Problem: How do I, without code duplication, declare dependency of all foo*.o to bar.h? Solutions so far: $(shell bash -c 'echo -ne foo{-pi,}.o'}: bar.h $(addsuffix .o, $(addprefix fo, o-pi o)): bar.h The first solution is not portable on systems that don't support bash, the second is a dirty solution since I could not figure out how to use empty strings in addprefix.

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  • Multithreading 2D gravity calculations

    - by Postman
    I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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  • Rendering MXML component only after actionscript is finished

    - by basicblock
    In my mxml file, I'm doing some calculations in the script tag, and binding them to a custom component. <fx:Script> <![CDATA[ [Bindable] public var calc1:Number; [Bindable] public var calc2:Number; private function init():void { calc1 = //calculation; calc2 = //calculation; } ]]> </fx:Script> <mycomp:Ball compfield1="{calc1}" compfield2="{calc2}"/> The problem is that the mxml component is being created before the actionscript is run. So when the component is created, it actually doesn't get calc1 and calc2 and it fails from that point. I know that binding happens after that, but the component and its functions have already started and have run with the null or 0 initial values. My solution was to create the component also in actionscript right after calc1 and calc2 have been created. This way I get to control precisely when it's created <fx:Script> <![CDATA[ [Bindable] public var calc1:Number; [Bindable] public var calc2:Number; private function init():void { calc1 = //calculation; calc2 = //calculation; var Ball:Ball = new Ball(calc1, calc2); } ]]> </fx:Script> but this is creating all kinds of other problems due to the way I've set up the component. Is there a way I can still use mxml to create the component, yet control that it the <myComp:Ball> gets created only after init() is run and calc1 calc2 evaluated?

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  • Code refactoring homework?

    - by Hira
    This is the code that I have to refactor for my homework: if (state == TEXAS) { rate = TX_RATE; amt = base * TX_RATE; calc = 2 * basis(amt) + extra(amt) * 1.05; } else if ((state == OHIO) || (state == MAINE)) { rate = (state == OHIO) ? OH_RATE : MN_RATE; amt = base * rate; calc = 2 * basis(amt) + extra(amt) * 1.05; if (state == OHIO) points = 2; } else { rate = 1; amt = base; calc = 2 * basis(amt) + extra(amt) * 1.05; } I have done something like this if (state == TEXAS) { rate = TX_RATE; calculation(rate); } else if ((state == OHIO) || (state == MAINE)) { rate = (state == OHIO) ? OH_RATE : MN_RATE; calculation(rate); if (state == OHIO) points = 2; } else { rate = 1; calculation(rate); } function calculation(rate) { amt = base * rate; calc = 2 * basis(amt) + extra(amt) * 1.05; } How could I have done better? Edit i have done code edit amt = base * rate;

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  • Strange performance behaviour

    - by plastilino
    I'm puzzled with this. In my machine Direct calculation: 375 ms Method calculation: 3594 ms, about TEN times SLOWER If I place the method calulation BEFORE the direct calculation, both times are SIMILAR. Woud you check it in your machine? class Test { static long COUNT = 50000 * 10000; private static long BEFORE; /*--------METHOD---------*/ public static final double hypotenuse(double a, double b) { return Math.sqrt(a * a + b * b); } /*--------TIMER---------*/ public static void getTime(String text) { if (BEFORE == 0) { BEFORE = System.currentTimeMillis(); return; } long now = System.currentTimeMillis(); long elapsed = (now - BEFORE); BEFORE = System.currentTimeMillis(); if (text.equals("")) { return; } String message = "\r\n" + text + "\r\n" + "Elapsed time: " + elapsed + " ms"; System.out.println(message); } public static void main(String[] args) { double a = 0.2223221101; double b = 122333.167; getTime(""); /*--------DIRECT CALCULATION---------*/ for (int i = 1; i < COUNT; i++) { Math.sqrt(a * a + b * b); } getTime("Direct: "); /*--------METHOD---------*/ for (int k = 1; k < COUNT; k++) { hypotenuse(a, b); } getTime("Method: "); } }

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  • How can I integrate advanced computations into a database field?

    - by ciclistadan
    My biological research involves the measurement of a cellular structure as it changes length throughout the course of observation (capturing images every minute for several hours). As my data sets have become larger I am trying to store them in an Access database, from which I would like to perform various queries about their changes in size. I know that the SELECT statement can incorporate some mathematical permutations, but I have been unable to incorporate many of my necessary calculations (probably due to my lack of knowledge). For example, one calculation involves determining the rate of change during specifically defined periods of growth. This calculation is entirely dependent on the raw data saved in the table, therefore I didn't this it would be appropriate to just calculate it in excel prior to entry into the field. So my question is, what would be the most appropriate method of performing this calculation. Should I attempt to string together a huge SELECT calculation in my QUERY, or is there a way to use another language (I know perl?) which can be called to populate the new query field? I'm not looking for someone to write the code, just where is it appropriate to incorporate each step. Also, I am currently using Office Access but would be interested in any mySQL answers as I may be moving to this platform at a later date. Thanks all!

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  • Programmatically use a server as the Build Server for multiple Project Collections

    Important: With this post you create an unsupported scenario by Microsoft. It will break your support for this server with Microsoft. So handle with care. I am the administrator an a TFS environment with a lot of Project Collections. In the supported configuration of Microsoft 2010 you need one Build Controller per Project Collection, and it is not supported to have multiple Build Controllers installed. Jim Lamb created a post how you can modify your system to change this behaviour. But since I have so many Project Collections, I automated this with the API of TFS. When you install a new build server via the UI, you do the following steps Register the build service (with this you hook the windows server into the build server environment) Add a new build controller Add a new build agent So in pseudo code, the code would look like foreach (projectCollection in GetAllProjectCollections) {       CreateNewWindowsService();       RegisterService();       AddNewController();       AddNewAgent(); } The following code fragements show you the most important parts of the method implementations. Attached is the full project. CreateNewWindowsService We create a new windows service with the SC command via the Diagnostics.Process class:             var pi = new ProcessStartInfo("sc.exe")                         {                             Arguments =                                 string.Format(                                     "create \"{0}\" start= auto binpath= \"C:\\Program Files\\Microsoft Team Foundation Server 2010\\Tools\\TfsBuildServiceHost.exe              /NamedInstance:{0}\" DisplayName= \"Visual Studio Team Foundation Build Service Host ({1})\"",                                     serviceHostName, tpcName)                         };            Process.Start(pi);             pi.Arguments = string.Format("failure {0} reset= 86400 actions= restart/60000", serviceHostName);            Process.Start(pi); RegisterService The trick in this method is that we set the NamedInstance static property. This property is Internal, so we need to set it through reflection. To get information on these you need nice Microsoft friends and the .Net reflector .             // Indicate which build service host instance we are using            typeof(BuildServiceHostUtilities).Assembly.GetType("Microsoft.TeamFoundation.Build.Config.BuildServiceHostProcess").InvokeMember("NamedInstance",              System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.SetProperty | System.Reflection.BindingFlags.Static, null, null, new object[] { serviceName });             // Create the build service host            serviceHost = buildServer.CreateBuildServiceHost(serviceName, endPoint);            serviceHost.Save();             // Register the build service host            BuildServiceHostUtilities.Register(serviceHost, user, password); AddNewController and AddNewAgent Once you have the BuildServerHost, the rest is pretty straightforward. There are methods on the BuildServerHost to modify the controllers and the agents                 controller = serviceHost.CreateBuildController(controllerName);                 agent = controller.ServiceHost.CreateBuildAgent(agentName, buildDirectory, controller);                controller.AddBuildAgent(agent); You have now seen the highlights of the application. If you need it and want to have sample information when you work in this area, download the app TFS2010_RegisterBuildServerToTPCs

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  • NetBeans Podcast 69

    - by TinuA
    Podcast Guests: Terrence Barr, Simon Ritter, Jaroslav Tulach (It's an all-Oracle lineup!) Download mp3: 47 Minutes – 39.5 mb Subscribe on iTunes NetBeans Community News with Geertjan and Tinu If you missed the first two Java Virtual Developer Day events in early May, there's still one more LIVE training left on May 28th. Sign up here to participate live in the APAC time zone or watch later ON DEMAND. Video: Get started with Vaadin development using NetBeans IDE NetBeans IDE was at JavaCro 2014 and at Hippo Get-together 2014 Another great lineup is in the works for NetBeans Day at JavaOne 2014. More details coming soon! NetBeans' Facebook page is almost at 40,000 Likes! Help us crack that milestone in the next few weeks! Other great ways to stay updated about NetBeans? Twitter and Google+. 09:28 / Terrence Barr - What to Know about Java Embedded Terrence Barr, a Senior Technologist and Principal Product Manager for Embedded and Mobile technologies at Oracle, discusses new features of the Java SE Embedded and Java ME Embedded platforms, and sheds some light on the differences between them and what they have to offer to developers. Learn more about Java SE Embedded Tutorial: Using Oracle Java SE Embedded Support in NetBeans IDE Learn more about Java ME Embedded Video: NetBeans IDE Support for Java ME 8 Video: Installing and Using Java ME SDK 8.0 Plugins in NetBeans IDE Follow Terrence Barr to keep up with news in the Embedded space: Blog and Twitter 26:02 / Simon Ritter - A Massive Serving of Raspberry Pi Oracle's Raspberry Pi virtual course is back by popular demand! Simon Ritter, the head of Oracle's Java Technology Evangelism team, chats about the second run of the free Java Embedded course (starting May 30th), what participants can expect to learn, NetBeans' support for Java ME development, and other Java trainings coming to a desktop, laptop or user group near you. Sign up for the Oracle MOOC: Develop Java Embedded Applications Using Raspberry Pi Find out when Simon Ritter and the Java Evangelism team are coming to a Java event or JUG in your area--follow them on Twitter: Simon Ritter Angela Caicedo Steven Chin Jim Weaver 36:58 / Jaroslav Tulach - A Perfect Translation Jaroslav Tulach returns to the NetBeans podcast with tales about the Japanese translation of the Practical API Design book, which he contends surpasses all previous translations, including the English edition! Order "Practical API Design" (Japanese Version)  Find out why the Japanese translation is the best edition yet *Have ideas for NetBeans Podcast topics? Send them to ">nbpodcast at netbeans dot org. *Subscribe to the official NetBeans page on Facebook! Check us out as well on Twitter, YouTube, and Google+.

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  • JavaOne Afterglow by Simon Ritter

    - by JuergenKress
    Last week was the eighteenth JavaOne conference and I thought it would be a good idea to write up my thoughts about how things went. Firstly thanks to Yoshio Terada for the photos, I didn't bother bringing a camera with me so it's good to have some pictures to add to the words. Things kicked off full-throttle on Sunday.  We had the Java Champions and JUG leaders breakfast, which was a great way to meet up with a lot of familiar faces and start talking all things Java.  At midday the show really started with the Strategy and Technical Keynotes.  This was always going to be tougher job than some years because there was no big shiny ball to reveal to the audience.  With the Java EE 7 spec being finalised a few months ago and Java SE 8, Java ME 8 and JDK8 not due until the start of next year there was not going to be any big announcement.  I thought both keynotes worked really well each focusing on the things most important to Java developers: Strategy One of the things that is becoming more and more prominent in many companies marketing is the Internet of Things (IoT).  We've moved from the conventional desktop/laptop environment to much more mobile connected computing with smart phones and tablets.  The next wave of the internet is not just billions of people connected, but 10s or 100s of billions of devices connected to the network, all generating data and providing much more precise control of almost any process you can imagine.  This ties into the ideas of Big Data and Cloud Computing, but implementation is certainly not without its challenges.  As Peter Utzschneider explained it's about three Vs: Volume, Velocity and Value.  All these devices will create huge volumes of data at very high speed; to avoid being overloaded these devices will need some sort of processing capabilities that can filter the useful data from the redundant.  The raw data then needs to be turned into useful information that has value.  To make this happen will require applications on devices, at gateways and on the back-end servers, all very tightly integrated.  This is where Java plays a pivotal role, write once, run everywhere becomes essential, having nine million developers fluent in the language makes it the defacto lingua franca of IoT.  There will be lots more information on how this will become a reality, so watch this space. Technical How do we make the IoT a reality, technically?  Using the game of chess Mark Reinhold, with the help of people like John Ceccarelli, Jasper Potts and Richard Bair, showed what you could do.  Using Java EE on the back end, Java SE and JavaFX on the desktop and Java ME Embedded and JavaFX on devices they showed a complete end-to-end demo. This was really impressive, using 3D features from JavaFX 8 (that's included with JDK8) to make a 3D animated Duke chess board.  Jasper also unveiled the "DukePad" a home made tablet using a Raspberry Pi, touch screen and accelerometer. Although the Raspberry Pi doesn't have earth shattering CPU performance (about the same level as a mid 1990s Pentium), it does have really quite good GPU performance so the GUI works really well.  The plans are all open sourced and available here.  One small, but very significant announcement was that Java SE will now be included with the NOOB and Raspbian Linux distros provided by the Raspberry Pi foundation (these can be found here).  No more hassle having to download and install the JDK after you've flashed your SD card OS image.  The finale was the Raspberry Pi powered chess playing robot.  Really very, very cool.  I talked to Jasper about this and he told me each of the chess pieces had been 3D printed and then he had to use acetone to give them a glossy finish (not sure what his wife thought of him spending hours in the kitchen in a gas mask!)  The way the robot arm worked was very impressive as it did not have any positioning data (like a potentiometer connected to each motor), but relied purely on carefully calibrated timings to get the arm to the right place.  Having done things like this myself in the past I know how easy it is to find a small error gets magnified into very big mistakes. Here's some pictures from the keynote: The "Dukepad" architecture Nice clear perspex case so you can see the innards. The very nice 3D chess set.  Maya's obviously a great tool. Read the full article here. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: Simon Ritter,Java One,OOW,Oracle OpenWorld,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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  • Sphere Texture Mapping shows visible seams

    - by AvengerDr
    As you can see from the above picture there is a visible seam in the texture mapping. The underlying mesh is a geosphere based on octahedron subdivisions. On that particular latitude, vertices have been duplicated. However there still is a visible seam. Here is how I calculate the UV coordinates: float longitude = (float)Math.Atan2(normal.X, -normal.Z); float latitude = (float)Math.Acos(normal.Y); float u = (float)(longitude / (Math.PI * 2.0) + 0.5); float v = (float)(latitude / Math.PI); Is this a problem in the coordinates or a mipmapping issue?

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  • Windows for IoT, continued

    - by Valter Minute
    Originally posted on: http://geekswithblogs.net/WindowsEmbeddedCookbook/archive/2014/08/05/windows-for-iot-continued.aspxI received many interesting feedbacks on my previous blog post and I tried to find some time to do some additional tests. Bert Kleinschmidt pointed out that pins 2,3 and 10 of the Galileo are connected directly to the SOC, while pin 13, the one used for the sample sketch is controlled via an I2C I/O expander. I changed my code to use pin 2 instead of 13 (just changing the variable assignment at the beginning of the code) and latency was greatly reduced. Now each pulse lasts for 1.44ms, 44% more than the expected time, but ways better that the result we got using pin 13. I also used SetThreadPriority to increase the priority of the thread that was running the sketch to THREAD_PRIORITY_HIGHEST but that didn't change the results. When I was using the I2C-controlled pin I tried the same and the timings got ways worse (increasing more than 10 times) and so I did not commented on that part, wanting to investigate the issua a bit more in detail. It seems that increasing the priority of the application thread impacts negatively the I2C communication. I tried to use also the Linux-based implementation (using a different Galileo board since the one provided by MS seems to use a different firmware) and the results of running the sample blink sketch modified to use pin 2 and blink the led for 1ms are similar to those we got on the same board running Windows. Here the difference between expected time and measured time is worse, getting around 3.2ms instead of 1 (320% compared to 150% using Windows but far from the 100.1% we got with the 8-bit Arduino). Both systems were not under load during the test, maybe loading some applications that use part of the CPU time would make those timings even less reliable, but I think that those numbers are enough to draw some conclusions. It may not be worth running a full OS if what you need is Arduino compatibility. The Arduino UNO is probably the best Arduino you can find to perform this kind of development. The Galileo running the Linux-based stack or running Windows for IoT is targeted to be a platform for "Internet of Things" devices, whatever that means. At the moment I don't see the "I" part of IoT. We have low level interfaces (SPI, I2C, the GPIO pins) that can be used to connect sensors but the support for connectivity is limited and the amount of work required to deliver some data to the cloud (using a secure HTTP request or a message queuing system like APMQS or MQTT) is still big and the rich OS underneath seems to not provide any help doing that.Why should I use sockets and can't access all the high level connectivity features we have on "full" Windows?I know that it's possible to use some third party libraries, try to build them using the Windows For IoT SDK etc. but this means re-inventing the wheel every time and can also lead to some IP concerns if used for products meant to be closed-source. I hope that MS and Intel (and others) will focus less on the "coolness" of running (some) Arduino sketches and more on providing a better platform to people that really want to design devices that leverage internet connectivity and the cloud processing power to deliver better products and services. Providing a reliable set of connectivity services would be a great start. Providing support for .NET would be even better, leaving native code available for hardware access etc. I know that those components may require additional storage and memory etc. So making the OS componentizable (or, at least, provide a way to install additional components) would be a great way to let developers pick the parts of the system they need to develop their solution, knowing that they will integrate well together. I can understand that the Arduino and Raspberry Pi* success may have attracted the attention of marketing departments worldwide and almost any new development board those days is promoted as "XXX response to Arduino" or "YYYY alternative to Raspberry Pi", but this is misleading and prevents companies from focusing on how to deliver good products and how to integrate "IoT" features with their existing offer to provide, at the end, a better product or service to their customers. Marketing is important, but can't decide the key features of a product (the OS) that is going to be used to develop full products for end customers integrating it with hardware and application software. I really like the "hackable" nature of open-source devices and like to see that companies are getting more and more open in releasing information, providing "hackable" devices and supporting developers with documentation, good samples etc. On the other side being able to run a sketch designed for an 8 bit microcontroller on a full-featured application processor may sound cool and an easy upgrade path for people that just experimented with sensors etc. on Arduino but it's not, in my humble opinion, the main path to follow for people who want to deliver real products.   *Shameless self-promotion: if you are looking for a good book in Italian about the Raspberry Pi , try mine: http://www.amazon.it/Raspberry-Pi-alluso-Digital-LifeStyle-ebook/dp/B00GYY3OKO

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  • determine collision angle on a rotating body

    - by jorb
    update: new diagram and updated description I have a contact listener set up to try and determine the side that a collision happened at relative to the a bodies rotation. One way to solve this is to find the value of the yellow angle between the red and blue vectors drawn above. The angle can be found by taking the arc cosine of the dot product of the two vectors (Evan pointed this out). One of my points of confusion is the difference in domain of the atan2 function html canvas coordinates and the Box2d rotation information. I know I have to account for this somehow... SS below questions: Does Box2D provide these angles more directly in the collision information? Am I even on the right track? If so, any hints? I have the following javascript so far: Ship.prototype.onCollide = function (other_ent,cx,cy) { var pos = this.body.GetPosition(); //collision position relative to body var d_cx = pos.x - cx; var d_cy = pos.y - cy; //length of initial vector var len = Math.sqrt(Math.pow(pos.x -cx,2) + Math.pow(pos.y-cy,2)); //body angle - can over rotate hence mod 2*Pi var ang = this.body.GetAngle() % (Math.PI * 2); //vector representing body's angle - same magnitude as the first var b_vx = len * Math.cos(ang); var b_vy = len * Math.sin(ang); //dot product of the two vectors var dot_prod = d_cx * b_vx + d_cy * b_vy; //new calculation of difference in angle - NOT WORKING! var d_ang = Math.acos(dot_prod); var side; if (Math.abs(d_ang) < Math.PI/2 ) side = "front"; else side = "back"; console.log("length",len); console.log("pos:",pos.x,pos.y); console.log("offs:",d_cx,d_cy); console.log("body vec",b_vx,b_vy); console.log("body angle:",ang); console.log("dot product",dot_prod); console.log("result:",d_ang); console.log("side",side); console.log("------------------------"); }

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  • It's here, it's here! OJEC 1.1 is here -- Oracle Java ME Embedded Client

    - by hinkmond
    Download it now! OJEC 1.1 has just been released and will run on your Linux/ARM, Linux/x86, or Linux/MIPS device. Get it before supplies run out! (Not really, it's software. How can it run out?) See: Download OJEC 1.1 now! Here's a quote: Oracle offers Java ME Embedded products to meet your specific Java Technology needs. Java ME is targeted for use on devices where a feature-rich Java platform is desirable, despite lacking the resources necessary to run the full Java SE Embedded environment. Try it on your Raspberry Pi! (If you can find where to buy a Raspberry Pi that is. Now that's something that can run out) Hinkmond

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  • Specifying force and angle in ApplyImpulse in box2d

    - by Deepak Mahalingam
    I need to apply an impulse on a object with a particular force and at a particular angle in Box2d. If I am right the syntax would be the following: body.GetBody().ApplyImpulse(new b2Vec2(direction, power),body.GetBody().GetWorldCenter()); The problem is my direction is in angles. I found a discussion where it was said that the way we can convert an angle into a vector would be as: new b2Vec2(Math.cos(angle*Math.PI/180),Math.sin(angle*Math.PI/180)); Now I am not sure how to combine these two. In other words, if I wish to apply a force of 30 units at an angle of 30 degrees at the center of the object, how should I do it?

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  • Possible to pass pygame data to memory map block?

    - by toozie21
    I am building a matrix out of addressable pixels and it will be run by a Pi (over the ethernet bus). The matrix will be 75 pixels wide and 20 pixels tall. As a side project, I thought it would be neat to run pong on it. I've seen some python based pong tutorials for Pi, but the problem is that they want to pass the data out to a screen via pygame.display function. I have access to pass pixel information using a memory map block, so is there anyway to do that with pygame instead of passing it out the video port? In case anyone is curious, this was the pong tutorial I was looking at: Pong Tutorial

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  • Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 2)

    - by hinkmond
    To start out our ghost hunting here at the Oracle Santa Clara campus office, we first need a ghost sensor. It's pretty easy to build one, since all we need to do is to create a circuit that can detect small fluctuations in the electromagnetic field, just like the fluctuations that ghosts cause when they pass by... Naturally, right? So, we build a static charge sensor and will use a Java Embedded app to monitor for changes in the sensor value, running analytics using Java technology on a Raspberry Pi. Bob's your uncle, and there you have it: a ghost sensor. See: Ghost Detector So, go out to Radio Shack and buy up these items: shopping list: 1 - NTE312 JFET N-channel transistor (this is in place of the MPF-102) 1 - Set of Jumper Wires 1 - LED 1 - 300 ohm resistor 1 - set of header pins Then, grab a flashlight, your Raspberry Pi, and come back here for more instructions... Don't be afraid... Yet. Hinkmond

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  • SlimDX: Lightning problem with Direct3D9

    - by Spi1988
    I am creating a simple application to get familiar with SlimDX library. I found some code written in MDX and I'm trying to convert it to run on SlimDX. I am having some problems with the light because everything is being shown as black. The code is: public partial class DirectTest : Form { private Device device= null; private float angle = 0.0f; Light light = new Light(); public DirectTest() { InitializeComponent(); this.Size = new Size(800, 600); this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.Opaque, true); } /// <summary> /// We will initialize our graphics device here /// </summary> public void InitializeGraphics() { PresentParameters pres_params = new PresentParameters() { Windowed = true, SwapEffect = SwapEffect.Discard }; device = new Device(new Direct3D(), 0, DeviceType.Hardware, this.Handle, CreateFlags.SoftwareVertexProcessing, pres_params); } private void SetupCamera() { device.SetRenderState(RenderState.CullMode, Cull.None); device.SetTransform(TransformState.World, Matrix.RotationAxis(new Vector3(angle / ((float)Math.PI * 2.0f), angle / ((float)Math.PI * 4.0f), angle / ((float)Math.PI * 6.0f)), angle / (float)Math.PI)); angle += 0.1f; device.SetTransform(TransformState.Projection, Matrix.PerspectiveFovLH((float)Math.PI / 4, this.Width / this.Height, 1.0f, 100.0f)); device.SetTransform(TransformState.View, Matrix.LookAtLH(new Vector3(0, 0, 5.0f), new Vector3(), new Vector3(0, 1, 0))); device.SetRenderState(RenderState.Lighting, false); } protected override void OnPaint(System.Windows.Forms.PaintEventArgs e) { device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.CornflowerBlue, 1.0f, 0); SetupCamera(); CustomVertex.PositionColored[] verts = new CustomVertex.PositionColored[3]; verts[0].Position = new Vector3(0.0f, 1.0f, 1.0f); verts[0].Normal = new Vector3(0.0f, 0.0f, -1.0f); verts[0].Color = System.Drawing.Color.White.ToArgb(); verts[1].Position = new Vector3(-1.0f, -1.0f, 1.0f); verts[1].Normal = new Vector3(0.0f, 0.0f, -1.0f); verts[1].Color = System.Drawing.Color.White.ToArgb(); verts[2].Position = new Vector3(1.0f, -1.0f, 1.0f); verts[2].Normal = new Vector3(0.0f, 0.0f, -1.0f); verts[2].Color = System.Drawing.Color.White.ToArgb(); light.Type = LightType.Point; light.Position = new Vector3(); light.Diffuse = System.Drawing.Color.White; light.Attenuation0 = 0.2f; light.Range = 10000.0f; device.SetLight(0, light); device.EnableLight(0, true); device.BeginScene(); device.VertexFormat = CustomVertex.PositionColored.format; device.DrawUserPrimitives<CustomVertex.PositionColored>(PrimitiveType.TriangleList, 1, verts); device.EndScene(); device.Present(); this.Invalidate(); } } } The Vertex Format that I am using is the following [StructLayout(LayoutKind.Sequential)] public struct PositionNormalColored { public Vector3 Position; public int Color; public Vector3 Normal; public static readonly VertexFormat format = VertexFormat.Diffuse | VertexFormat.Position | VertexFormat.Normal; } Any suggestions on what the problem might be? Thanks in Advance

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  • Why isn't my algorithm for find the biggest and smallest inputs working?

    - by Matt Ellen
    I have started a new job, and with it comes a new language: Ironpython. Thankfully a good language :D Before starting I got to grips with Python on the whole, but that was only a week's worth of learning. Now I'm writing actual code. I've been charged with writing an algorithm that finds the best input parameter to collect data with. The basic algorithm is (as I've been instructed): Set the input parameter to a good guess Start collecting data When data is available stop collecting find the highest point If the point before this (i.e. for the previous parameter value) was higher and the point before that was lower then we've found the max otherwise the input parameter is increased by the initial guess. goto 2 If the max is found then the min needs to be found. To do this the algorithm carries on increasing the input, but by 1/10 of the max, until the current point is greater than the previous point and the point before that is also greater. Once the min is found then the algorithm stops. Currently I have a simplified data generator outputting the sin of the input, so that I know that the min value should be PI and the max value should be PI/2 The main Python code looks like this (don't worry, this is just for my edification, I don't write real code like this): import sys sys.path.append(r"F:\Programming Source\C#\PythonHelp\PythonHelp\bin\Debug") import clr clr.AddReferenceToFile("PythonHelpClasses.dll") import PythonHelpClasses from PHCStruct import Helper from System import Math helper = Helper() def run(): b = PythonHelpClasses.Executor() a = PythonHelpClasses.HasAnEvent() b.Input = 0.0 helper.__init__() def AnEventHandler(e): b.Stop() h = helper h.lastLastVal, h.lastVal, h.currentVal = h.lastVal, h.currentVal, e.Number if h.lastLastVal < h.lastVal and h.currentVal < h.lastVal and h.NotPast90: h.NotPast90 = False h.bestInput = h.lastInput inputInc = 0.0 if h.NotPast90: inputInc = Math.PI/10.0 else: inputInc = h.bestInput/10.0 if h.lastLastVal > h.lastVal and h.currentVal > h.lastVal and h.NotPast180: h.NotPast180 = False if h.NotPast180: h.lastInput, b.Input = b.Input, b.Input + inputInc b.Start(a) else: print "Best input:", h.bestInput print "Last input:", h.lastInput b.Stop() a.AnEvent += AnEventHandler b.Start(a) PHCStruct.py: class Helper(): def __init__(self): self.currentVal = 0 self.lastVal = 0 self.lastLastVal = 0 self.NotPast90 = True self.NotPast180 = True self.bestInput = 0 self.lastInput = 0 PythonHelpClasses has two small classes I wrote in C# before I realised how to do it in Ironpython. Executor runs a delegate asynchronously while it's running member is true. The important code: public void Start(HasAnEvent hae) { running = true; RunDelegate r = new RunDelegate(hae.UpdateNumber); AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar = r.BeginInvoke(Input, ac, null); } public void Stop() { running = false; } public void UpdateDone(IAsyncResult ar) { RunDelegate r = (RunDelegate)((AsyncResult)ar).AsyncDelegate; r.EndInvoke(ar); if (running) { AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar2 = r.BeginInvoke(Input, ac, null); } } HasAnEvent has a function that generates the sin of its input and fires an event with that result as its argument. i.e.: public void UpdateNumber(double val) { AnEventArgs e = new AnEventArgs(Math.Sin(val)); System.Threading.Thread.Sleep(1000); if (null != AnEvent) { AnEvent(e); } } The sleep is in there just to slow things down a bit. The problem I am getting is that the algorithm is not coming up with the best input being PI/2 and the final input being PI, but I can't see why. Also the best and final inputs are different each time I run the programme. Can anyone see why? Also when the algorithm terminates the best and final inputs are printed to the screen multiple times, not just once. Can someone explain why?

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  • How to get an ARM CPU clock speed in Linux?

    - by MiKy
    I have an ARM-based embedded machine based on S3C2416 board. According to the specifications I have available there should be a 533 MHz ARM9 (ARM926EJ-S according to /proc/cpuinfo), however the software running on it "feels" slow, compared to the same software on my Android phone with a 528MHz ARM CPU. /proc/cpuinfo tells me that BogoMIPS is 266.24. I know that I should not trust BogoMIPS regarding performance ("Bogo" = bogus), however I would like to get a measurement on the actual CPU speed. On x86, I could use the rdtsc instruction to get the time stamp counter, wait a second (sleep(1)), read the counter again to get an approximation on the CPU speed, and according to my experience, this value was close enough to the real CPU speed. How can I find the actual CPU speed of given ARM processor? Update I found this simple Pi calculator, which I compiled both for my Android phone and the ARM board. The results are as follows: S3C2416 # cat /proc/cpuinfo Processor : ARM926EJ-S rev 5 (v5l) BogoMIPS : 266.24 Features : swp half fastmult edsp java ... #./pi_arm 10000 Calculation of PI using FFT and AGM, ver. LG1.1.2-MP1.5.2a.memsave ... 8.50 sec. (real time) Android # cat /proc/cpuinfo Processor : ARMv6-compatible processor rev 2 (v6l) BogoMIPS : 527.56 Features : swp half thumb fastmult edsp java # ./pi_android 10000 Calculation of PI using FFT and AGM, ver. LG1.1.2-MP1.5.2a.memsave ... 5.95 sec. (real time) So it seems that the ARM926EJ-S is slower than my Android phone, but not twice slower as I would expect by the BogoMIPS figures. I am still unsure about the clock speed of the ARM9 CPU.

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