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  • How to find minimum of nonlinear, multivariate function using Newton's method (code not linear algeb

    - by Norman Ramsey
    I'm trying to do some parameter estimation and want to choose parameter estimates that minimize the square error in a predicted equation over about 30 variables. If the equation were linear, I would just compute the 30 partial derivatives, set them all to zero, and use a linear-equation solver. But unfortunately the equation is nonlinear and so are its derivatives. If the equation were over a single variable, I would just use Newton's method (also known as Newton-Raphson). The Web is rich in examples and code to implement Newton's method for functions of a single variable. Given that I have about 30 variables, how can I program a numeric solution to this problem using Newton's method? I have the equation in closed form and can compute the first and second derivatives, but I don't know quite how to proceed from there. I have found a large number of treatments on the web, but they quickly get into heavy matrix notation. I've found something moderately helpful on Wikipedia, but I'm having trouble translating it into code. Where I'm worried about breaking down is in the matrix algebra and matrix inversions. I can invert a matrix with a linear-equation solver but I'm worried about getting the right rows and columns, avoiding transposition errors, and so on. To be quite concrete: I want to work with tables mapping variables to their values. I can write a function of such a table that returns the square error given such a table as argument. I can also create functions that return a partial derivative with respect to any given variable. I have a reasonable starting estimate for the values in the table, so I'm not worried about convergence. I'm not sure how to write the loop that uses an estimate (table of value for each variable), the function, and a table of partial-derivative functions to produce a new estimate. That last is what I'd like help with. Any direct help or pointers to good sources will be warmly appreciated. Edit: Since I have the first and second derivatives in closed form, I would like to take advantage of them and avoid more slowly converging methods like simplex searches.

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  • Virtual Earth Shape Rendering Performance

    - by Mike
    I am overlaying a transparent image on my VEMap control by rendering it as a single VEShape. The shape changes sizes dynamically depeding on the zoom level of my map and can be as large as 4000*4000px. In older browsers such as IE6 and early versions of Firefox 2.x, map control performance degrades rapidly when my shape gets larger than 1500*1500px. The mouse pointer moves slowly and the map responds very slowly to events. I don't see this issue at all in newer browsers (IE7+). Are there any workarounds to boost performance of rendering a large shape for IE6 users?

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  • Objective-C method implementation nuances

    - by altdotnetgeek
    I have just started to develop for the iPhone and am in the process of learning Objective-C. I have seen some code that implements a method in the @implementation side of a class like this: -(void)myMethod; { // method body } What makes this interesting is that there is no mention of myMethod in the @interface for the class. I tried a sample project with this and when I compile I get a warning from XCode that myMethod may not be seen by the calling code. Can anyone tell me what is going on? Thanks!

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  • cannot get ip address on a virtual machine

    - by user175084
    so i have a code which gets me the ip address of a machine i am wroking on. so if my gui is published on the server and i access it from my local machine it gives me tha address of my local machine and when i access the gui from the server itself it gives me the server address.. which is fine. But when i put the gui on a VM server and run it from a VM server itself i dont get the ip address. this works fine if i access it from another machine but does not work only when accesing gui on VM server.. please help me out as i get this value ":::1" here is my code: string ipaddress; //string ipaddress = Request.ServerVariables["LOCAL_ADDR"]; string ipaddress = Request.ServerVariables["HTTP_X_FORWARDED_FOR"]; if (ipaddress == "" || ipaddress == null) string ipaddress = Request.ServerVariables["REMOTE_ADDR"]; Label5.Text = ipaddress; thank you

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  • Virtual-machine running from DVD ?

    - by umanga
    Greetings all, I have this application which uses Tomcat and PostgreSQL (only involve database reads, no writes). I need to make this application runnable from a DVD.(target platform is Windows). So I was thinking to do these: 1) In a VirtualMachine (i prefer virtualbox) install lightweight linux distro. 2) Install Tomcat and Postgre, 3) Write virtualmachine into DVD which loads above virtualmachine image automatically when executed. But I am not quite sure whether I can do step 3.Or is it possible ? Any tips?

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  • execute javascript method after completing code behind method ?

    - by James123
    I can execute below callback() method after completion of document.getElementById('btnDownload').click(); .This Click is Code behind method. Now it is executing immediatly. I want wait "Click()" process done then Execute callback(); method. function LoadPopup() { // find the popup behavior this._popup = $find('mdlPopup'); // show the popup this._popup.show(); // synchronously run the server side validation ... document.getElementById('btnDownload').click(); callback(); } function callback() { this._popup = $find('mdlPopup'); // hide the popup this._popup.hide(); alert("hi"); }

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  • Java method overloading + double dispatch

    - by Max
    Can anybody explain in detail the reason the overloaded method print(Parent parent) is invoked when working with Child instance in my test piece of code? Any pecularities of virtual methods or methods overloading/resolution in Java involved here? Any direct reference to Java Lang Spec? Which term describes this behaviour? Thanks a lot. public class InheritancePlay { public static class Parent { public void doJob(Worker worker) { System.out.println("this is " + this.getClass().getName()); worker.print(this); } } public static class Child extends Parent { } public static class Worker { public void print(Parent parent) { System.out.println("Why this method resolution happens?"); } public void print(Child child) { System.out.println("This is not called"); } } public static void main(String[] args) { Child child = new Child(); Worker worker = new Worker(); child.doJob(worker); } }

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  • C++ method chaining including class constructor

    - by jena
    Hello, I'm trying to implement method chaining in C++, which turns out to be quite easy if the constructor call of a class is a separate statement, e.g: Foo foo; foo.bar().baz(); But as soon as the constructor call becomes part of the method chain, the compiler complains about expecting ";" in place of "." immediately after the constructor call: Foo foo().bar().baz(); I'm wondering now if this is actually possible in C++. Here is my test class: class Foo { public: Foo() { } Foo& bar() { return *this; } Foo& baz() { return *this; } }; I also found an example for "fluent interfaces" in C++ (http://en.wikipedia.org/wiki/Fluent_interface#C.2B.2B) which seems to be exactly what I'm searching for. However, I get the same compiler error for that code. Thanks in advance for any hint. Best, Jean

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  • Real server, Multiple IP Addresses, HyperV Virtual Server, How to partition IPs across real and Virtual NICs

    - by Steven_W
    This is a slightly difficult problem to explain without same basic background information - I'll try and refine the question later as necessary Originally, I have a single hosted server (Win 2008R2) with the following range of 8 IP addresses. - Single NIC - IP: x.x.128.72 -> x.x.128.79 - Subnet: x.x.255.192 - GW: x.x.128.65 After installing Hyper-V and setting up a single virtual server on the same box, I then wanted to assign one of the IP addresses to the virtual server, leaving everything else running normally. -- Firstly, I tried using the "External" network, but (even after setting IPs on the "Virtual Adapter" similar to Here but struggled to get networking running at all. I needed to keep the server running (otherwise I would have spent more time pursuing this approach) Q1 ... Was this a sensible thing to do ? Should I have carried on down this route ? -- I then decided to try different approach - Set the HyperV network to "Internal" (visible to Management OS) - Physical NIC - IP: x.x.128.72 -> x.x.128.75 - Subnet: x.x.255.192 - GW: x.x.128.65 - Virtual NIC - IP: x.x.128.78 - Subnet: x.x.255.252 - GW: x.x.128.72 ... { The same as the IP of the physical NIC ) - Virtual OS-NIC - IP: x.x.128.77 - Subnet: x.x.255.252 - GW: x.x.128.78 ... { The same as the IP of the host virtual-NIC ) -- Surprisingly enough, this approach actually worked, and I was able to connect from all the following: - Internet to/from physical NIC (x.x.128.72) - physical NIC (x.x.128.72) to virtual-OS-NIC (x.x.128.77) e.g. testing via ping + FTP - Internet to/from virtual-OS-NIC (x.x.128.72) -- The problem I have is that this approach seems to only last for a short while (a few hours). After this time, it seems that I lose the ability to connect from Virtual-OS-NIC to/from the internet (but I can still connect from the host-OS to the virtual-OS and from the host-OS to the internet) I have re-tested this a couple of times with the same results ... I leave the server on for a few hours (e.g. overnight), and when I come back in the morning, the Virtual-OS loses the ability to route to the internet -- I'm not quite sure what to look at next (or whether I'm going about this completely the wrong way ) One "possible relevant item" is that the host-OS is also running RRAS (Routing and Remote Access), but this is only to run a simple VPN -- Q2 - Wheat should I be looking at next ? (Any good references / recommendations of what to try) Would appreciate any thoughts or comments (even if you tell me I'm going about this the wrong way)

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  • Is it possible to limit how much CPU a virtual machine can use with VMWare Player?

    - by Raz
    Is it possible to limit how much CPU a virtual machine can use with VMWare Player? I use VMWare to run a Windows XP virtual machine. I want to keep it on in the background all the time. The real computer runs Windows 7 and is sometimes a little bit short of memory. That's why I want to check if I can throttle the VM down to the bare minimum to keep it running in the background constantly without interfering too much.

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  • How to stream sound from an esx virtual machine ?

    - by Adrien
    Hi, I try to play sound from my monitoring application, which is an xp virtual machine on VMware ESX 3, on a physical machine with a real sound card, but I can not add from the ESX console sound card. Currently, I transmit sound with opening an RDP session and play it in this session. I would like to play sound without openning RDP session, do you have a solution to add a virtual sound card and then stream it with vlc?

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  • Is it possible to run several virtual machines each with independent mouse+keyboard on a single PC?

    - by chiurox
    My goal is to instead of buying 4 separate basic PCs (plus the obvious peripherals), buy just one fast PC and the peripherals. I'm wondering if I can use a more powerful computer, say, one with core i7 and plenty of RAM, with 2 video cards (total of 4 monitor outputs) to run 4 or more virtual machines (WinXPs) so instead of having 4 individual machines, I'll be having just one. However, the catch is, is it possible to have a pair of mouse and keyboard + input/output audio for each of these virtual machines?

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  • Can I install a Windows 8 Pro upgrade in a virtual machine?

    - by Dean Schulze
    I bought a Lenovo 430K with Windows 7 Home Premium and upgraded it to Windows 8 Pro. I created a DVD from which I installed the Windows 8 Pro upgrade. I'm underwhelmed with Windows 8, however. I want to install Linux as the host OS and run Windows 8 Pro as a guest OS. Will the Windows 8 Pro DVD that I created install Windows 8 Pro in a virtual machine, or would that virtual machine have to have Windows 7 installed first in order to install the upgrade?

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  • Top - what does Virtual memory size mean? ...linux/ubuntu

    - by user42159
    I am running Top to monitor my server performance and 2 of my java processes show virtual memory of upto 800MB-1GB. Is that a bad thing? What does virtual memory mean? And oh btw, I have swap of 1GB and it shoes 0% used. So I am confused. Java process = 1 Tomcat server + my own java deamon Server = Ubuntu 9.10 (karmic)

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  • How can I copy an XP Mode virtual machine from one computer to another?

    - by Investor5555
    Is it possible to copy an XP Mode Virtual PC image from one computer to a completely different computer (not on the network, not related in any way whatsoever)? I tried this, but it only would seem to work on the same computer: http://www.sevenforums.com/tutorials/21904-virtual-xp-machine-copy.html When I copy it to another computer and modify the settings as described above, the cursor just jumps around all over the screen and never starts.

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  • Can I read a smartcard in a virtual machine?

    - by endian
    My employer requires a smartcard to login to their web-based remote working platform. I want to access this platform by using a Remote Desktop Connection on to my Windows 7 Virtual Machine, with the smartcard plugged into my home PC. However, whilst I can see the smartcard on my home PC, it doesn't appear in the virtual machine, despite me having "Smart Cards" enabled in the Local Resources page of Remote Desktop Connection. Is it possible to get this working?

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  • Virtualnetwork with virtualbox

    - by vpereira
    I would like to test a firewall solution. For that i would like to create a virtual network, without contact with my network and configure two virtual ethernet cards in my firewall. is that possible? say that my virtual machine has two ethernets? If with virtualbox is not possible, is it possible with any VM solution? To create virtual network and virtual devices in my virtual operational system

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  • Calling overridden parent method from parent method

    - by Yisroel
    Heres the situation. Component B extends component A and overrides the init method to accept a different parameter. A also has a create method that calls init. If i have an instance of B and i call create, its calling the wrong init - it calls init in B, where i need it to call init in A. I dont want to call super.init() as there may not always be a super. Is there any way to specify to call the init in the parent component?

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  • Hyper-V virtual machine can't be migrated to a specific host in the cluster

    - by Massimo
    I have a three-node Hyper-V cluster running on Windows Server 2008 R2 which is working quite flawlessly: there are no errors, live migration works, all hosts can and will happily run all virtual machines, and so on. But one specific virtual machinee is trying to make me go mad: it works on two nodes of the cluster, but not on the third one. Whenever I try to move the VM to that node, be it in a live migration or with the VM powered off, it always fails. In the event log of the host these events are logged: Source: Hyper-V-VMMS Event ID: 16300 Cannot load a virtual machine configuration: General access denied error (0x80070005) (Virtual machine ID <GUID>) Source: Hyper-V-VMMS Evend ID: 20100 The Virtual Machine Management Service failed to register the configuration for the virtual machine '<GUID>' at 'C:\ClusterStorage\<PATH>\<VM>': General access denied error (0x80070005) Source: Hyper-V-High-Availability Event ID: 21102 'Virtual Machine Configuration <VM>' failed to register the virtual machine with the virtual machine management service. All other VMs can be moved to/from the offending host, and the offending VM can be moved between the other two hosts. Also, this is not a storage problem, because there are other VMs in the same cluster volume, and the host has no troubles running them. What's going on here?

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  • Java method keyword "final" and its use

    - by Lukas Eder
    When I create complex type hierarchies (several levels, several types per level), I like to use the final keyword on methods implementing some interface declaration. An example: interface Garble { int zork(); } interface Gnarf extends Garble { /** * This is the same as calling {@link #zblah(0)} */ int zblah(); int zblah(int defaultZblah); } And then abstract class AbstractGarble implements Garble { @Override public final int zork() { ... } } abstract class AbstractGnarf extends AbstractGarble implements Gnarf { // Here I absolutely want to fix the default behaviour of zblah // No Gnarf shouldn't be allowed to set 1 as the default, for instance @Override public final int zblah() { return zblah(0); } // This method is not implemented here, but in a subclass @Override public abstract int zblah(int defaultZblah); } I do this for several reasons: It helps me develop the type hierarchy. When I add a class to the hierarchy, it is very clear, what methods I have to implement, and what methods I may not override (in case I forgot the details about the hierarchy) I think overriding concrete stuff is bad according to design principles and patterns, such as the template method pattern. I don't want other developers or my users do it. So the final keyword works perfectly for me. My question is: Why is it used so rarely in the wild? Can you show me some examples / reasons where final (in a similar case to mine) would be very bad?

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