Search Results

Search found 43645 results on 1746 pages for 'good computer'.

Page 196/1746 | < Previous Page | 192 193 194 195 196 197 198 199 200 201 202 203  | Next Page >

• Are spinlocks a good choice for a memory allocator?

  - by dsimcha

  I've suggested to the maintainers of the D programming language runtime a few times that the memory allocator/garbage collector should use spinlocks instead of regular OS critical sections. This hasn't really caught on. Here are the reasons I think spinlocks would be better: At least in synthetic benchmarks that I did, it's several times faster than OS critical sections when there's contention for the memory allocator/GC lock. Edit: Empirically, using spinlocks didn't even have measurable overhead in a single-core environment, probably because locks need to be held for such a short period of time in a memory allocator. Memory allocations and similar operations usually take a small fraction of a timeslice, and even a small fraction of the time a context switch takes, making it silly to context switch in the case of contention. A garbage collection in the implementation in question stops the world anyhow. There won't be any spinning during a collection. Are there any good reasons not to use spinlocks in a memory allocator/garbage collector implementation?

  Read the article

• When is it a good idea to use the CSS display property?

  - by allyourcode

  I think I first learned of this property when I thought "I should put this list of items in a ul, but I want it to be laid out horizontally. I wonder if I can do that with CSS?" When I googled this, I found a couple of sites suggesting that I create a CSS rule that would change the value of the display property of the li elements to inline. I've also seen the suggestion that a div (or other block element) be given display: table-cell in order to force the vertical align property to work. These techniques seem kind of hacky. Does that make sense? This might not be a good analogy, but it seems like trying to ride a car as if it were a motorcycle. Yeah, I could replace the steering wheel with handle bars, wear a helmet, and remove all the passenger seating, but how the heck is a car going to drive on two wheels??

  Read the article

• Are there any good reasons why I should not use Python?

  - by coppro

  I've heard from reliable sources that Python is a great language that every programmer can learn, but I've heard so much good about it that I'm clearly not getting the whole picture. I'm considering spending more time to learn it, and I've heard more than I need about its virtues (to the point where I've started recommending it having never really used it), so I want to know its drawbacks, flaws, issues, and every single minor point of irritation you've ever had (preferably with explanations readable to one who doesn't program Python, such as with an example in another language). Convince me not to try it out.

  Read the article

• Is this a good approach to execute a list of operations on a data structure in Python?

  - by Sridhar Iyer

  I have a dictionary of data, the key is the file name and the value is another dictionary of its attribute values. Now I'd like to pass this data structure to various functions, each of which runs some test on the attribute and returns True/False. One approach would be to call each function one by one explicitly from the main code. However I can do something like this: #MYmodule.py class Mymodule: def MYfunc1(self): ... def MYfunc2(self): ... #main.py import Mymodule ... #fill the data structure ... #Now call all the functions in Mymodule one by one for funcs in dir(Mymodule): if funcs[:2]=='MY': result=Mymodule.__dict__.get(funcs)(dataStructure) The advantage of this approach is that implementation of main class needn't change when I add more logic/tests to MYmodule. Is this a good way to solve the problem at hand? Are there better alternatives to this solution?

  Read the article

• android localization: Is it a good practice to have only needed resource to put in localized folder?

  - by MobileDev123

  Hi, My application has 4 languages in it. However only one module needs to be localized out of 5, This module has 4 layout files and some images, remaining files can be there in default layout folder and drawable folders. My question is : is it good practice to put only needed files in localization folders, if I leave other files in its respective folders and don't copy them in translation folders, does my application throw NullPointerException when my application runs in other language? and Does android market have any size limit? (Also being a BB developer,AFAIK they do not allow OTA, if the application size grows more than 3 mb) [In case i need to copy the layout and image files]. Note about NullPointerException : it throws in string if you omit some string in localization and application runs in that particular locale. Thanks

  Read the article

• What's a good way to have sample data on the iPhone/iPad?

  - by MikeN

  I have an iPad application that pulls in all of its data from an external web service. I am working on building in a demo mode that will use a cache of demo data stored on the device so it can be demoed and tried out without the web service connection (or an internet connection.) Is there a project or good practices standard to follow to model this type of sample data? I'm expecting JSON arrays/Dictionaries back from my web service, how could I build a function that uses hardcoded data to create the NSMutableData object I'd expect to get back from a JSON web request?

  Read the article

• Is PThread a good choice for multi-platorm C/C++ multi-threading program?

  - by RogerV

  Been doing mostly Java and smattering of .NET for last five years and haven't written any significant C or C++ during that time. So have been away from that scene for a while. If I want to write a C or C++ program today that does some multi-threading and is source code portable across Windows, Mac OS X, and Linux/Unix - is PThread a good choice? The C or C++ code won't be doing any GUI, so won't need to worry with any of that. For the Windows platform, I don't want to bring a lot of Unix baggage, though, in terms of unix emulation runtime libraries. Would prefer a PThread API for Windows that is a thin-as-possible wrapper over existing Windows threading APIs. ADDENDUM EDIT: Am leaning toward going with boost:thread - I also want to be able to use C++ try/catch exception handling too. And even though my program will be rather minimal and not particularly OOPish, I like to encapsulate using class and namespace - as opposed to C disembodied functions.

  Read the article

• When using out parameters in a function, is it good practice to initialize them in the function?

  - by adambox

  I have a function that uses out parameters to return multiple values to the caller. I would like to initialize them in the function, but I wasn't sure if that's a bad idea since you don't know when you call the function that it's going to change the values right away. The caller might assume that after the function returns, if whatever it was doing didn't work, the values would be whatever they were initialized to in the caller. Is it ok / good for me to initialize in the function? Example: public static void SomeFunction(int ixID, out string sSomething) { sSomething = ""; sSomething = something(ixID); if (sSomething = "") { somethingelse(); sSomething = "bar" } }

  Read the article

• How to override virtual function in good style? [C++]

  - by Knowing me knowing you

  Hi, guys I know this question is very basic but I've met in few publications (websites, books) different style of override virtual function. What I mean is: if I have base class: class Base { public: virtual void f() = 0; }; in some publications I saw that to override this some authors would just say: void f(); and some would still repeat the virtual keyword before void. Which form of overwriting is in good style? Thank you for your answers.

  Read the article

• Is it a good design to return value by parameter?

  - by aztack

  bool is_something_ok(int param,SomeStruct* p) { bool is_ok = false; // check if is_ok if(is_ok) // set p to some valid value else // set p to NULL return is_ok; } this function return true and set p to a valid value if "something is ok" otherwise return false and set p to NULL Is that a good or bad design? personally, i feel uncomfortable when i use it. If there is no document and comment, i really don know how to use it. BTW:Is there some authoritative book/article about API design?

  Read the article

• Will Haskell be a good choice for my task?

  - by Narzanka

  I'm starting a new project and don't know which language to use. My 'must have' requirements are: Be able to run on Windows/LinuxMacOs natively (native executable) - user should be able to just run the exe (when on Windows for example) and see the results. No runtimes/interpreters (no jvm, clr, etc) - one file download should be enough to run the application. Full unicode support. Be able to manipulate OS threads (create them, run multiple tasks in parallel on multi-core CPUs, etc). Be reasonably fast (Python level performance and better). To have some kind of standard library that does low-level, mundane tasks. Not very niche and have some community behind it to be able to ask questions. My 'nice to have' requirements are: Language should be functional It should have good string manipulation capabilities (not necessarily regex) Not extremely hard to learn I'm thinking about Haskell now but keeping in mind OCaml as well. Please advice if my choice is correct.

  Read the article

• is it good to write multiple time(separate) <script type="text/javascript"> on one php page?

  - by I Like PHP

  i m using many tiny java script code at one php page, i always write java script code in below style <script type="text/javascript"> // <![CDATA[ ----code 1--------- // ]]> </script> <script type="text/javascript"> // <![CDATA[ ----code 2----- // ]]> </script> <script type="text/javascript"> // <![CDATA[ $(document).ready.(function(){ }); // ]]> </script> i want to know that is it good practice to write separate <script type="text/javascript"></script> on same page or we have to write all java script code under one time declaration

  Read the article

• How to overwrite virtual fnc in good style? [C++]

  - by atch

  Hi, guys I know this question is very basic but I've met in few publications (websites, books) different style of overwriting virtual function. What I mean is: if I have base class: class Base { public: virtual void f() = 0; }; in some publications I saw that to overwrite this some authors would just say: void f(); and some would still repeat the virtual keyword before void. Which form of overwriting is in good style? Thank you for your answers.

  Read the article

• Is it a good idea to include a large text variable in compiled code?

  - by gladman

  I am writing a program that produces a formatted file for the user, but it's not only producing the formatted file, it does more. I want to distribute a single binary to the end user and when the user runs the program, it will generate the xml file for the user with appropriate data. In order to achieve this, I want to give the file contents to a char array variable that is compiled in code. When the user runs the program, I will write out the char file to generate an xml file for the user. char* buffers = "a xml format file contents, \ this represent many block text \ from a file,..."; I have two questions. Q1. Do you have any other ideas for how to compile my file contents into binary, i.e, distribute as one binary file. Q2. Is this even a good idea as I described above?

  Read the article

• Is there a unique computer identifier that can be used reliably even in a virtual machine?

  - by SaUce

  I'm writing a small client program to be run on a terminal server. I'm looking for a way to make sure that it will only run on this server and in case it is removed from the server it will not function. I understand that there is no perfect way of securing it to make it impossible to ran on other platforms, but I want to make it hard enough to prevent 95% of people to try anything. The other 5% who can hack it is not my concern. I was looking at different Unique Identifiers like Processor ID, Windows Product ID, Computer GUID and other UIs. Because the terminal server is a virtual machine, I cannot locate anything that is completely unique to this machine. Any ideas on what I should look into to make this 95% secure. I do not have time or the need to make it as secure as possible because it will defeat the purpose of the application itself. I do not want to user MAC address. Even though it is unique to each machine it can be easily spoofed. As far as Microsoft Product ID, because our system team clones VM servers and we use corporate volume key, I found already two servers that I have access to that have same Product ID Number. I have no Idea how many others out there that have same Product ID By 95% and 5% I just simply wanted to illustrate how far i want to go with securing this software. I do not have precise statistics on how many people can do what. I believe I might need to change my approach and instead of trying to identify the machine, I will be better off by identifying the user and create group based permission for access to this software.

  Read the article

• Using GCC 4.2 to compile *.mm files is very very slow, but LLVM has done a very good job, any difference?

  - by jianhua

  My project is obj-c and C++ hybirid, filled with by both *.m and *.mm. When compiling, if choose GCC 4.2, *.m obj-c source files compile speed is very fast but *.mm very very slow, but LLVM 2.0 can do a very good job, it is very fast for both *.m and *.mm. My question: Is there any difference between LLVM and GCC 4.2 during compliling *.mm files? why GCC 3.2 is so slow? Any ieda or discussion will be appreciated, thanks in advance. ENV: XCODE 4.0.1

  Read the article

• Ask the Readers: How Do You Remote Desktop Access Distant Computers?

  - by Jason Fitzpatrick

  You’re at a computer at point A, but the computer you want to interact with is at point B, and the only thing connecting you is a series of network switches and cabling. How do you comfortably control the remote computer? While there are a variety of ways to control a computer from afar, sometimes there’s just no good substitute for accessing the user interface as if you were sitting at the computer–a feat made possibly by remote desktop software. This week we want to hear about both your favorite remote desktop tool and your best tips for getting the most out of a remote desktop session–from banishing lag to improving mouse-cursor tracking, any tips are fair game. Sound off in the comments below with your remote desktop tips and then check back in on Friday for the What You Said roundup. Java is Insecure and Awful, It’s Time to Disable It, and Here’s How What Are the Windows A: and B: Drives Used For? HTG Explains: What is DNS?

  Read the article

• Why won't my Internet stay connected?

  - by Aubrey

  I recently updated to Ubuntu 12.04, from Ubuntu 10.04, and my Internet, USB760 Novetel Verizon-Wireless Mobile Broadband, will connect after a minute of me starting the computer up. But after a while it will disconnect and the only way to reconnect it is to restart the computer. Even then, sometimes it won't work. I've also noticed that since I've upgraded the computer, the computer will randomly enter into Power Save mode, and then it will tell me to log back in. I've done nothing to provoke it, other than using the Internet. I was wondering, could the entering into Power Save mode and the Internet disconnecting be somehow connected? I've updated the computer every time it asks me to do so, but it doesn't seem to be helping. If Ubuntu 10.04 would still be supported by next year, I would downgrade. But I have no other choice than to stick with 12.04. Any help would be greatly appreciated! Thanks!

  Read the article

• A way to return multiple return values from a method: put method inside class representing return value. Is it a good design?

  - by john smith optional

  I need to return 2 values from a method. My approach is as follows: create an inner class with 2 fields that will be used to keep those 2 values put the method inside that class instantiate the class and call the method. The only thing that will be changed in the method is that in the end it will assign those 2 values to the fields of the instance. Then I can address those values by referencing to the fields of that object. Is it a good design and why?

  Read the article

• How to set-up my own cloud server?

  - by WMRKameleon

  I am a student, 17 years of age and wanting to access all of my files at greatest ease. i would like to have a system like this: Computer A, B and C are the computers on which I work and to which the files should be available. Server A is located in my room and I can install Ubuntu on it. What is the goal? I want to edit files on computer A (e.g.) and computer A should update the file on my server, afterwards the server should update the files on computer B and C. (The same goes for editing files on computer B, afterwards the server has to update the files on A and C.) How am I able to set-up a network like this? It is about music, movies, pictures, documents... Thanks for those who are going to reply!

  Read the article

• In 10.10, USB 3.0 PCI Express card recognized by lspci but not lsusb or dmesg. How to fix?

  - by Paul

  Asus N PC, runs 10.10 x86_64 The Asus N comes with 4 usb 2.0 ports, each labelled 2.0 on the case. Attempting to add two usb 3.0 ports to be provided by a generic usb 3.0 pci express card installed in the pci expres slot. The new card says usb 3.0 and has the blue ports. The card is installed into the laptop unpowered, then the laptop is powered on and boots normally. Nothing happens when a USB 3.0 flash drive is inserted into the usb 3.0 port. uname -a Linux drpaulbrewer-N90SV 2.6.35.8 #1 SMP Fri Jan 14 15:54:11 EST 2011 x86_64 GNU/Linux lspci -v 00:00.0 Host bridge: Silicon Integrated Systems [SiS] 671MX Subsystem: ASUSTeK Computer Inc. Device 1b27 Flags: bus master, medium devsel, latency 64 Kernel modules: sis-agp 00:01.0 PCI bridge: Silicon Integrated Systems [SiS] PCI-to-PCI bridge (prog-if 00 [Normal decode]) Flags: bus master, fast devsel, latency 0 Bus: primary=00, secondary=01, subordinate=01, sec-latency=0 I/O behind bridge: 0000d000-0000dfff Memory behind bridge: fa000000-fdefffff Prefetchable memory behind bridge: 00000000d0000000-00000000dfffffff Capabilities: [d0] Express Root Port (Slot+), MSI 00 Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit- Capabilities: [f4] Power Management version 2 Capabilities: [70] Subsystem: Silicon Integrated Systems [SiS] PCI-to-PCI bridge Kernel driver in use: pcieport 00:02.0 ISA bridge: Silicon Integrated Systems [SiS] SiS968 [MuTIOL Media IO] (rev 01) Flags: bus master, medium devsel, latency 0 00:02.5 IDE interface: Silicon Integrated Systems [SiS] 5513 [IDE] (rev 01) (prog-if 80 [Master]) Subsystem: ASUSTeK Computer Inc. Device 1b27 Flags: bus master, medium devsel, latency 128 I/O ports at 01f0 [size=8] I/O ports at 03f4 [size=1] I/O ports at 0170 [size=8] I/O ports at 0374 [size=1] I/O ports at ffe0 [size=16] Capabilities: [58] Power Management version 2 Kernel driver in use: pata_sis 00:03.0 USB Controller: Silicon Integrated Systems [SiS] USB 1.1 Controller (rev 0f) (prog-if 10 [OHCI]) Subsystem: ASUSTeK Computer Inc. Device 1b27 Flags: bus master, medium devsel, latency 64, IRQ 20 Memory at f9fff000 (32-bit, non-prefetchable) [size=4K] Kernel driver in use: ohci_hcd 00:03.1 USB Controller: Silicon Integrated Systems [SiS] USB 1.1 Controller (rev 0f) (prog-if 10 [OHCI]) Subsystem: ASUSTeK Computer Inc. Device 1b27 Flags: bus master, medium devsel, latency 64, IRQ 21 Memory at f9ffe000 (32-bit, non-prefetchable) [size=4K] Kernel driver in use: ohci_hcd 00:03.3 USB Controller: Silicon Integrated Systems [SiS] USB 2.0 Controller (prog-if 20 [EHCI]) Subsystem: ASUSTeK Computer Inc. Device 1b27 Flags: bus master, medium devsel, latency 64, IRQ 22 Memory at f9ffd000 (32-bit, non-prefetchable) [size=4K] Capabilities: [50] Power Management version 2 Kernel driver in use: ehci_hcd 00:04.0 Ethernet controller: Silicon Integrated Systems [SiS] 191 Gigabit Ethernet Adapter (rev 02) Subsystem: ASUSTeK Computer Inc. Device 11f5 Flags: bus master, medium devsel, latency 0, IRQ 19 Memory at f9ffcc00 (32-bit, non-prefetchable) [size=128] I/O ports at cc00 [size=128] Capabilities: [40] Power Management version 2 Kernel driver in use: sis190 Kernel modules: sis190 00:05.0 IDE interface: Silicon Integrated Systems [SiS] SATA Controller / IDE mode (rev 03) (prog-if 8f [Master SecP SecO PriP PriO]) Subsystem: ASUSTeK Computer Inc. Device 1b27 Flags: bus master, medium devsel, latency 64, IRQ 17 I/O ports at c800 [size=8] I/O ports at c400 [size=4] I/O ports at c000 [size=8] I/O ports at bc00 [size=4] I/O ports at b800 [size=16] I/O ports at b400 [size=128] Capabilities: [58] Power Management version 2 Kernel driver in use: sata_sis Kernel modules: sata_sis 00:06.0 PCI bridge: Silicon Integrated Systems [SiS] PCI-to-PCI bridge (prog-if 00 [Normal decode]) Flags: bus master, fast devsel, latency 0 Bus: primary=00, secondary=02, subordinate=02, sec-latency=0 Memory behind bridge: fdf00000-fdffffff Capabilities: [b0] Subsystem: Silicon Integrated Systems [SiS] Device 0004 Capabilities: [c0] MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities: [d0] Express Root Port (Slot+), MSI 00 Capabilities: [f4] Power Management version 2 Kernel driver in use: pcieport 00:07.0 PCI bridge: Silicon Integrated Systems [SiS] PCI-to-PCI bridge (prog-if 00 [Normal decode]) Flags: bus master, fast devsel, latency 0 Bus: primary=00, secondary=03, subordinate=06, sec-latency=0 I/O behind bridge: 0000e000-0000efff Memory behind bridge: fe000000-febfffff Prefetchable memory behind bridge: 00000000f6000000-00000000f8ffffff Capabilities: [b0] Subsystem: Silicon Integrated Systems [SiS] Device 0004 Capabilities: [c0] MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities: [d0] Express Root Port (Slot+), MSI 00 Capabilities: [f4] Power Management version 2 Kernel driver in use: pcieport 00:0f.0 Audio device: Silicon Integrated Systems [SiS] Azalia Audio Controller Subsystem: ASUSTeK Computer Inc. Device 17b3 Flags: bus master, medium devsel, latency 0, IRQ 18 Memory at f9ff4000 (32-bit, non-prefetchable) [size=16K] Capabilities: [50] Power Management version 2 Kernel driver in use: HDA Intel Kernel modules: snd-hda-intel 01:00.0 VGA compatible controller: nVidia Corporation G96 [GeForce GT 130M] (rev a1) (prog-if 00 [VGA controller]) Subsystem: ASUSTeK Computer Inc. Device 2021 Flags: bus master, fast devsel, latency 0, IRQ 16 Memory at fc000000 (32-bit, non-prefetchable) [size=16M] Memory at d0000000 (64-bit, prefetchable) [size=256M] Memory at fa000000 (64-bit, non-prefetchable) [size=32M] I/O ports at dc00 [size=128] [virtual] Expansion ROM at fde80000 [disabled] [size=512K] Capabilities: [60] Power Management version 3 Capabilities: [68] MSI: Enable- Count=1/1 Maskable- 64bit+ Capabilities: [78] Express Endpoint, MSI 00 Capabilities: [b4] Vendor Specific Information: Len=14 <?> Kernel driver in use: nvidia Kernel modules: nvidia-current, nouveau, nvidiafb 02:00.0 Network controller: Atheros Communications Inc. AR928X Wireless Network Adapter (PCI-Express) (rev 01) Subsystem: Device 1a3b:1067 Flags: bus master, fast devsel, latency 0, IRQ 16 Memory at fdff0000 (64-bit, non-prefetchable) [size=64K] Capabilities: [40] Power Management version 2 Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit- Capabilities: [60] Express Legacy Endpoint, MSI 00 Capabilities: [90] MSI-X: Enable- Count=1 Masked- Kernel driver in use: ath9k Kernel modules: ath9k 03:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03) (prog-if 30) Flags: bus master, fast devsel, latency 0, IRQ 10 Memory at febfe000 (64-bit, non-prefetchable) [size=8K] Capabilities: [50] Power Management version 3 Capabilities: [70] MSI: Enable- Count=1/8 Maskable- 64bit+ Capabilities: [90] MSI-X: Enable- Count=8 Masked- Capabilities: [a0] Express Endpoint, MSI 00 lsusb Bus 003 Device 002: ID 0b05:1751 ASUSTek Computer, Inc. BT-253 Bluetooth Adapter Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 004: ID 0bda:0158 Realtek Semiconductor Corp. USB 2.0 multicard reader Bus 001 Device 002: ID 04f2:b071 Chicony Electronics Co., Ltd 2.0M UVC Webcam / CNF7129 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub dmesg trying to post dmesg exceeded the stackexchange posting limit of 30K... but nothing there is usb 3.0

  Read the article

• I/O errors are reported when I try to install Ubuntu, but the SMART data is good. Is my hard disk dying?

  - by James

  When I try to install linux, it tells me there is an input output error on dev sda. I have tried both Ubuntu and Mint on two different computers. So that narrows it down to the hdd. After hours of googling and trying different things I tried making the hardrive ext4 with gparted but that comes up with an error. This makes me think that the hdd is bad. There are a few reasons I think the hdd isn't bad. I can use the hdd in windows fully. Windows and gparted disk health checks both say it is fine. Its SMART data is all good. So... help?

  Read the article

• Ubuntu boots into terminal

  - by DKuntz2

  When I turn on my computer (a CR-48), I keep loading tty1. I have tried xstart, and all I get is: Fatal server error: Could not create lock file in /tmp/.tX0-lock When I attempted to make the directory (both sudo and not), I received these two errors: sudo: Can't open /var/lib/sudo/don/tty2: Read-only file system (I've gotten other tty's for different virtual terminals) mkdir: cannot create directory '/tmp/tX0-lock': Read-only file system Before I got to the only terminal state, I had the computer moving a few files from a network server to the computer, I put it to sleep without stopping the transfers, and started the computer again away from my home network, and attempted to stop the transfers, the computer than restarted. Running sudo reboot puts me right back in the virtual terminal, and I can't get into any sort of x application.

  Read the article

• big lie about programmer [closed]

  - by gcc

  About computer engineering/ computer science, Can you give me big lie ? ex : - There is no need to attend school ( study computer engineering ). Because every one can code ( write program ) - Programmer cannot do web design , they can only write code - there are no difference between software engineer and coder EDIT: A lie is a type of deception in the form of an untruthful statement, especially with the intention to deceive others. Why someone try to deceive other people especially customer ? I think they try to prove they are real computer engineer without having diploma in computer science. If you look in that manner to my answer you can easily understand what I want

  Read the article

• Come up with a real-world problem in which only the best solution will do (a problem from Introduction to algorithms) [closed]

  - by Mike

  EDITED (I realized that the question certainly needs a context) The problem 1.1-5 in the book of Thomas Cormen et al Introduction to algorithms is: "Come up with a real-world problem in which only the best solution will do. Then come up with one in which a solution that is “approximately” the best is good enough." I'm interested in its first statement. And (from my understanding) it is asked to name a real-world problem where only the exact solution will work as opposed to a real-world problem where good-enough solution will be ok. So what is the difference between the exact and good enough solution. Consider some physics problem for example the simulation of the fulid flow in the permeable medium. To make this simulation happen some simplyfing assumptions have to be made when deriving a mathematical model. Otherwise the model becomes at least complex and unsolvable. Virtually any particle in the universe has its influence on the fluid flow. But not all particles are equal. Those that form the permeable medium are much more influental than the ones located light years away. Then when the mathematical model needs to be solved an exact solution can rarely be found unless the mathematical model is simple enough (wich probably means the model isn't close to reality). We take an approximate numerical method and after hours of coding and days of verification come up with the program or algorithm which is a solution. And if the model and an algorithm give results close to a real problem by some degree that is good enough soultion. Its worth noting the difference between exact solution algorithm and exact computation result. When considering real-world problems and real-world computation machines I believe all physical problems solutions where any calculations are taken can not be exact because universal physical constants are represented approximately in the computer. Any numbers are represented with the limited precision, at least limited by amount of memory available to computing machine. I can imagine plenty of problems where good-enough, good to some degree solution will work, like train scheduling, automated trading, satellite orbit calculation, health care expert systems. In that cases exact solutions can't be derived due to constraints on computation time, limitations in computer memory or due to the nature of problems. I googled this question and like what this guy suggests: there're kinds of mathematical problems that need exact solutions (little note here: because the question is taken from the book "Introduction to algorithms" the term "solution" means an algorithm or a program, which in this case gives exact answer on each input). But that's probably more of theoretical interest. So I would like to narrow down the question to: What are the real-world practical problems where only the best (exact) solution algorithm or program will do (but not the good-enough solution)? There are problems like breaking of cryptographic ciphers where only exact solution matters in practice and again in practice the process of deciphering without knowing a secret should take reasonable amount of time. Returning to the original question this is the problem where good-enough (fast-enough) solution will do there's no practical need in instant crack though it's desired. So the quality of "best" can be understood in any sense: exact, fastest, requiring least memory, having minimal possible network traffic etc. And still I want this question to be theoretical if possible. In a sense that there may be example of computer X that has limited resource R of amount Y where the best solution to problem P is the one that takes not more than available Y for inputs of size N*Y. But that's the problem of finding solution for P on computer X which is... well, good enough. My final thought that we live in a world where it is required from programming solutions to practical purposes to be good enough. In rare cases really very very good but still not the best ones. Isn't it? :) If it's not can you provide an example? Or can you name any such unsolved problem of practical interest?

  Read the article

< Previous Page | 192 193 194 195 196 197 198 199 200 201 202 203  | Next Page >