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  • Why do arrays in java choose the biggest? [closed]

    - by Trycon
    I'm new to java so I was reading my book with these code: public class mainb1 { public static void main (String[] args) { //datatype name = expression; //food int min, max; int num[] = new int[10]; num[0]=99; num[1]=90; num[2]=-100; num[3]=100; num[4]=23; num[5]=50; num[6]=123; num[7]=3123; num[8]=2; num[9]=923; min=max=num[1]; for(int x=0;x<10;x++) { if(num[x]<min)min=num[x]; if(num[x]>max)max=num[x]; } System.out.println("Min: "+min+" max: "+max); } } It chose the biggest and the smallest. I don't get it if max was 99, then the last one that is lesser than min is 2? How did this array choose to pick the smallest and the biggest? Can someone explain?

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  • Why does mobile first responsive design tend to not use max-width queries alongside the min-width queries?

    - by Sam
    First off, I understand the basic principles behind mobile first responsive web design, and totally agree with them. But one thing I don't understand: In my experience, not all styles for small screens can be used for the larger version of a website. For example, usually smaller versions tend to have larger clickable areas, hamburger navigation, etc. So I sometimes have to override these specific styles, aside from just progressively enhancing the base styles. So I was wondering: why is max-width rarely mentioned (or used) in the context of mobile-first responsive web design? Because it looks like it could be used to isolate styles for smaller screens that are not useful for larger screens, and would thus prevent unnecessary duplication of code. A quote which mentions min-width as typically mobile-first, but not max-width: Mobile first, from a coding perspective, means that your base style is typically a single-column, fully-fluid layout. You use @media (min-width: whatever) to add a grid-based layout on top of that. from: http://gomakethings.com/mobile-first-and-internet-explorer/ EDIT: So to be more specific: I was wondering if there is a reason to exclude max-width from a mobile-first responsive design (as it seems like it can be useful for writing your css as DRY as possible, as some styles for small screens will not be used for bigger screens).

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  • how to pull and display range (min-max) data for each page in pagination?

    - by Ty W
    I have a table of data that is searchable and sortable, but likely to produce hundreds or thousands of results for broad searches. Assuming the user searches for "foo" and sorts the foos in descending price order I'd like to show a quick-jump select menu like so: <option value="1">Page 1 ($25,000,000 - $1,625,000)</option> <option value="2">Page 2 ($1,600,000 - $1,095,000)</option> <option value="3">Page 3 ($1,095,000 - $815,000)</option> <option value="4">Page 4 ($799,900 - $699,000)</option> ... Is there an efficient way of querying for this information directly from the DB? I've been grabbing all of the matching records and using PHP to calculate the min and max value for each page which seems inefficient and likely to cause scaling problems. The only possible technique I've been able to come up with is some way of having a calculated variable that increments every X records (X records to a page), grouping by that, and selecting MIN/MAX for each page grouping... unfortunately I haven't been able to come up with a way to generate that variable.

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  • Web Site Performance and Assembly Versioning

    - by capgpilk
    I originally wanted to write this post in one, but there is quite a large amount of information which can be broken down into different areas, so I am going to publish it in three posts. Minification and Concatination of JavaScript and CSS Files – this post Versioning Combined Files Using Subversion – published shortly Versioning Combined Files Using Mercurial – published shortly Website Performance There are many ways to improve web site performance, two areas are reducing the amount of data that is served up from the web server and reducing the number of files that are requested. Here I will outline the process of minimizing and concatenating your javascript and css files automatically at build time of your visual studio web site/ application. To edit the project file in Visual Studio, you need to first unload it by right clicking the project in Solution Explorer. I prefer to do this in a third party tool such as Notepad++ and save it there forcing VS to reload it each time I make a change as the whole process in Visual Studio can be a bit tedious. Now you have the project file, you will notice that it is an MSBuild project file. I am going to use a fantastic utility from Microsoft called Ajax Minifier. This tool minifies both javascript and css. 1. Import the tasks for AjaxMin choosing the location you installed to. I keep all third party utilities in a Tools directory within my solution structure and source control. This way I know I can get the entire solution from source control without worrying about what other tools I need to get the project to build locally. 1: <Import Project="..\Tools\MicrosoftAjaxMinifier\AjaxMin.tasks" /> 2. Now create ItemGroups for all your js and css files like this. Separating out your non minified files and minified files. This can go in the AfterBuild container. 1: <Target Name="AfterBuild"> 2:  3: <!-- Javascript files that need minimizing --> 4: <ItemGroup> 5: <JSMin Include="Scripts\jqModal.js" /> 6: <JSMin Include="Scripts\jquery.jcarousel.js" /> 7: <JSMin Include="Scripts\shadowbox.js" /> 8: </ItemGroup> 9: <!-- CSS files that need minimizing --> 10: <ItemGroup> 11: <CSSMin Include="Content\Site.css" /> 12: <CSSMin Include="Content\themes\base\jquery-ui.css" /> 13: <CSSMin Include="Content\shadowbox.css" /> 14: </ItemGroup>   1: <!-- Javascript files to combine --> 2: <ItemGroup> 3: <JSCat Include="Scripts\jqModal.min.js" /> 4: <JSCat Include="Scripts\jquery.jcarousel.min.js" /> 5: <JSCat Include="Scripts\shadowbox.min.js" /> 6: </ItemGroup> 7: <!-- CSS files to combine --> 8: <ItemGroup> 9: <CSSCat Include="Content\Site.min.css" /> 10: <CSSCat Include="Content\themes\base\jquery-ui.min.css" /> 11: <CSSCat Include="Content\shadowbox.min.css" /> 12: </ItemGroup>   3. Call AjaxMin to do the crunching. 1: <Message Text="Minimizing JS and CSS Files..." Importance="High" /> 2: <AjaxMin JsSourceFiles="@(JSMin)" JsSourceExtensionPattern="\.js$" 3: JsTargetExtension=".min.js" JsEvalTreatment="MakeImmediateSafe" 4: CssSourceFiles="@(CSSMin)" CssSourceExtensionPattern="\.css$" 5: CssTargetExtension=".min.css" /> This will create the *.min.css and *.min.js files in the same directory the original files were. 4. Now concatenate the minified files into one for javascript and another for css. Here we write out the files with a default file name. In later posts I will cover versioning these files the same as your project assembly again to help performance. 1: <Message Text="Concat JS Files..." Importance="High" /> 2: <ReadLinesFromFile File="%(JSCat.Identity)"> 3: <Output TaskParameter="Lines" ItemName="JSLinesSite" /> 4: </ReadLinesFromFile> 5: <WriteLinestoFile File="Scripts\site-script.combined.min.js" Lines="@(JSLinesSite)" 6: Overwrite="true" /> 7: <Message Text="Concat CSS Files..." Importance="High" /> 8: <ReadLinesFromFile File="%(CSSCat.Identity)"> 9: <Output TaskParameter="Lines" ItemName="CSSLinesSite" /> 10: </ReadLinesFromFile> 11: <WriteLinestoFile File="Content\site-style.combined.min.css" Lines="@(CSSLinesSite)" 12: Overwrite="true" /> 5. Save the project file, if you have Visual Studio open it will ask you to reload the project. You can now run a build and these minified and combined files will be created automatically. 6. Finally reference these minified combined files in your web page. In the next two posts I will cover versioning these files to match your assembly.

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  • SSH port forwarding through Windows machine

    - by Leonardo Ramé
    is it possible to connect to an SSH server only accessible from inside a network, using a Windows machine without SSH as a gateway?. Let me clarify my question with a sketch: Me (Linux machine)--- WIN (Windows without SSHD)---LIN (Linux with SSHD). Machine Me, is the PC I'm using to connect to LIN through WIN. WIN is accessible from the outside, it has an RDESKTOP port open, and LIN is only accessible from inside the network. Hope you understand the question.

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  • Computer won't reboot without waiting for a while

    - by Benjamin
    I've got an unusual problem with my computer. When ever I reboot my computer it won't boot, I get a few beeps from the BIOS and nothing else, however if I wait for a few minuets the computer will boot perfectly. I tried to count the beeps and I get around 7-9 of them; the first two are noticeably closer together than the rest. [Edit: I'm now reasonably confident it's 1 long followed by 8 short beeps. That would be a display related issue: http://www.bioscentral.com/beepcodes/amibeep.htm] My BIOS is American Megatrends Inc and version P1.80, the Motherboard is an ASRock X58 Extreme (both according to dmidecode) Here's an output from LSPCI, I'm not sure what else might be useful but I can provide whatever's asked. 00:00.0 Host bridge: Intel Corporation 5520/5500/X58 I/O Hub to ESI Port (rev 13) 00:01.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 1 (rev 13) 00:03.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 3 (rev 13) 00:07.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 7 (rev 13) 00:14.0 PIC: Intel Corporation 5520/5500/X58 I/O Hub System Management Registers (rev 13) 00:14.1 PIC: Intel Corporation 5520/5500/X58 I/O Hub GPIO and Scratch Pad Registers (rev 13) 00:14.2 PIC: Intel Corporation 5520/5500/X58 I/O Hub Control Status and RAS Registers (rev 13) 00:14.3 PIC: Intel Corporation 5520/5500/X58 I/O Hub Throttle Registers (rev 13) 00:1a.0 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #4 00:1a.1 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #5 00:1a.2 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #6 00:1a.7 USB controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #2 00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller 00:1c.0 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 1 00:1c.1 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Port 2 00:1c.5 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 6 00:1d.0 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #1 00:1d.1 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #2 00:1d.2 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #3 00:1d.7 USB controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #1 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 90) 00:1f.0 ISA bridge: Intel Corporation 82801JIR (ICH10R) LPC Interface Controller 00:1f.2 SATA controller: Intel Corporation 82801JI (ICH10 Family) SATA AHCI Controller 00:1f.3 SMBus: Intel Corporation 82801JI (ICH10 Family) SMBus Controller 01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03) 02:00.0 FireWire (IEEE 1394): VIA Technologies, Inc. VT6315 Series Firewire Controller 02:00.1 IDE interface: VIA Technologies, Inc. VT6415 PATA IDE Host Controller (rev a0) 03:00.0 SATA controller: JMicron Technology Corp. JMB360 AHCI Controller (rev 02) 05:00.0 VGA compatible controller: nVidia Corporation GT200b [GeForce GTX 285] (rev a1) ff:00.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture Generic Non-Core Registers (rev 05) ff:00.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture System Address Decoder (rev 05) ff:02.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Link 0 (rev 05) ff:02.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Physical 0 (rev 05) ff:03.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller (rev 05) ff:03.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Target Address Decoder (rev 05) ff:03.4 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Test Registers (rev 05) ff:04.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Control Registers (rev 05) ff:04.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Address Registers (rev 05) ff:04.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Rank Registers (rev 05) ff:04.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Thermal Control Registers (rev 05) ff:05.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Control Registers (rev 05) ff:05.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Address Registers (rev 05) ff:05.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Rank Registers (rev 05) ff:05.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Thermal Control Registers (rev 05) ff:06.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Control Registers (rev 05) ff:06.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Address Registers (rev 05) ff:06.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Rank Registers (rev 05) ff:06.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Thermal Control Registers (rev 05) Update: ok I installed lm-sensors and here's the output. coretemp-isa-0000 Adapter: ISA adapter Core 0: +58.0°C (high = +80.0°C, crit = +100.0°C) Core 1: +59.0°C (high = +80.0°C, crit = +100.0°C) Core 2: +58.0°C (high = +80.0°C, crit = +100.0°C) Core 3: +57.0°C (high = +80.0°C, crit = +100.0°C) it8720-isa-0a10 Adapter: ISA adapter in0: +0.93 V (min = +0.00 V, max = +4.08 V) in1: +0.06 V (min = +0.00 V, max = +4.08 V) in2: +3.25 V (min = +0.00 V, max = +4.08 V) +5V: +2.91 V (min = +0.00 V, max = +4.08 V) in4: +3.04 V (min = +0.00 V, max = +4.08 V) in5: +2.94 V (min = +0.00 V, max = +4.08 V) in6: +2.14 V (min = +0.00 V, max = +4.08 V) 5VSB: +2.96 V (min = +0.00 V, max = +4.08 V) Vbat: +3.28 V fan1: 1869 RPM (min = 0 RPM) fan2: 0 RPM (min = 0 RPM) fan3: 0 RPM (min = 0 RPM) fan4: 1106 RPM (min = -1 RPM) fan5: 225000 RPM (min = -1 RPM) temp1: +39.0°C (low = +0.0°C, high = +127.0°C) sensor = thermistor temp2: +56.0°C (low = +0.0°C, high = +127.0°C) sensor = thermistor temp3: +127.0°C (low = +0.0°C, high = +127.0°C) sensor = thermistor cpu0_vid: +1.650 V intrusion0: ALARM If it helps here's the summery from sensors-detect Driver `it87': * ISA bus, address 0xa10 Chip `ITE IT8720F Super IO Sensors' (confidence: 9) Driver `adt7475': * Bus `NVIDIA i2c adapter 3 at 5:00.0' Busdriver `nvidia', I2C address 0x2e Chip `Analog Devices ADT7473' (confidence: 5) Driver `coretemp': * Chip `Intel digital thermal sensor' (confidence: 9)

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  • how do i ininitialize a float to it's max/min value?

    - by Faken
    How do i hard code an absolute maximum or minimum value for a float or double? I want to search out the max/min of an array by simply iterating through and catching the largest. There are also positive and negative infinity for floats, should i use those instead? if so, how do i denote that in my code?

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  • how do I initialize a float to its max/min value?

    - by Faken
    How do I hard code an absolute maximum or minimum value for a float or double? I want to search out the max/min of an array by simply iterating through and catching the largest. There are also positive and negative infinity for floats, should I use those instead? If so, how do I denote that in my code?

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  • OpenCv Error ( unhandeld exeption) after execute

    - by hamza
    Hi , i m using VS2010 i m trting to make a gray image more bright , the code did compile normaly but no change in the seconde picture , and an error message ( undhadled exeception .. .. ) showed up after that the execute is done showed up here is a peace of my code : int main(int argc, _TCHAR* argv[]) { IplImage *img = cvLoadImage("mra.jpg"); if (!img) { printf("Error: Couldn't open the image file.\n"); return 1; } //IplImage* new_image = getlargersize(img); double Min , Max ; Min = Max = 0 ; Max_Min (img , &Min , &Max); cout<<"the max value in the picture is :"<<Min<<" and the minimum value is :"<<Max<<endl ; IplImage* img2 = eclaircir(Min ,Max ,img); cvNamedWindow("Image:", CV_WINDOW_AUTOSIZE); cvNamedWindow("Image2:", CV_WINDOW_AUTOSIZE); cvShowImage("Image2:", img2); cvShowImage("Image:", img); cvWaitKey(0); cvDestroyWindow("Image2:"); cvDestroyWindow("Image:"); cvReleaseImage(&img2); cvReleaseImage(&img); return 0; } void Max_Min(IplImage* temp , double *min , double *max ){ CvScalar pix ; for (int i = 0 ; i < temp->height ; i++){ for (int j = 0 ; j < temp->width ; j++){ pix = cvGet2D(temp , i , j); if ( pix.val[0] >= *max ){ *max = pix.val[0]; } if ( pix.val[0] <= *min){ *min = pix.val[0]; } } } } IplImage* eclaircir (double min , double max , IplImage* image){ double temp = max - min ; CvScalar pix ; for (int i = 0 ; i < image->height ; i++){ for (int j = 0 ; j < image->width ; j++){ pix = cvGet2D(image , i , j); pix.val[0] = ( pix.val[0] - min)*255 ; pix.val[0] = pix.val[0]/temp ; cvSet2D(image , i , j , pix ); } } return image ; } thanks

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  • Round time to 5 minute nearest SQL Server

    - by Drako
    i don't know if it can be usefull to somebody but I went crazy looking for a solution and ended up doing it myself. Here is a function that (according to a date passed as parameter), returns the same date and approximate time to the nearest multiple of 5. It is a slow query, so if anyone has a better solution, it is welcome. A greeting. CREATE FUNCTION [dbo].[RoundTime] (@Time DATETIME) RETURNS DATETIME AS BEGIN DECLARE @min nvarchar(50) DECLARE @val int DECLARE @hour int DECLARE @temp int DECLARE @day datetime DECLARE @date datetime SET @date = CONVERT(DATETIME, @Time, 120) SET @day = (select DATEADD(dd, 0, DATEDIFF(dd, 0, @date))) SET @hour = (select datepart(hour,@date)) SET @min = (select datepart(minute,@date)) IF LEN(@min) > 1 BEGIN SET @val = CAST(substring(@min, 2, 1) as int) END else BEGIN SET @val = CAST(substring(@min, 1, 1) as int) END IF @val <= 2 BEGIN SET @val = CAST(CAST(@min as int) - @val as int) END else BEGIN IF (@val <> 5) BEGIN SET @temp = 5 - CAST(@min%5 as int) SET @val = CAST(CAST(@min as int) + @temp as int) END IF (@val = 60) BEGIN SET @val = 0 SET @hour = @hour + 1 END IF (@hour = 24) BEGIN SET @day = DATEADD(day,1,@day) SET @hour = 0 SET @min = 0 END END RETURN CONVERT(datetime, CAST(DATEPART(YYYY, @day) as nvarchar) + '-' + CAST(DATEPART(MM, @day) as nvarchar) + '-' + CAST(DATEPART(dd, @day) as nvarchar) + ' ' + CAST(@hour as nvarchar) + ':' + CAST(@val as nvarchar), 120) END

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  • Ball bouncing at a certain angle and efficiency computations

    - by X Y
    I would like to make a pong game with a small twist (for now). Every time the ball bounces off one of the paddles i want it to be under a certain angle (between a min and a max). I simply can't wrap my head around how to actually do it (i have some thoughts and such but i simply cannot implement them properly - i feel i'm overcomplicating things). Here's an image with a small explanation . One other problem would be that the conditions for bouncing have to be different for every edge. For example, in the picture, on the two small horizontal edges i do not want a perfectly vertical bounce when in the middle of the edge but rather a constant angle (pi/4 maybe) in either direction depending on the collision point (before the middle of the edge, or after). All of my collisions are done with the Separating Axes Theorem (and seem to work fine). I'm looking for something efficient because i want to add a lot of things later on (maybe polygons with many edges and such). So i need to keep to a minimum the amount of checking done every frame. The collision algorithm begins testing whenever the bounding boxes of the paddle and the ball intersect. Is there something better to test for possible collisions every frame? (more efficient in the long run,with many more objects etc, not necessarily easy to code). I'm going to post the code for my game: Paddle Class public class Paddle : Microsoft.Xna.Framework.DrawableGameComponent { #region Private Members private SpriteBatch spriteBatch; private ContentManager contentManager; private bool keybEnabled; private bool isLeftPaddle; private Texture2D paddleSprite; private Vector2 paddlePosition; private float paddleSpeedY; private Vector2 paddleScale = new Vector2(1f, 1f); private const float DEFAULT_Y_SPEED = 150; private Vector2[] Normals2Edges; private Vector2[] Vertices = new Vector2[4]; private List<Vector2> lst = new List<Vector2>(); private Vector2 Edge; #endregion #region Properties public float Speed { get {return paddleSpeedY; } set { paddleSpeedY = value; } } public Vector2[] Normal2EdgesVector { get { NormalsToEdges(this.isLeftPaddle); return Normals2Edges; } } public Vector2[] VertexVector { get { return Vertices; } } public Vector2 Scale { get { return paddleScale; } set { paddleScale = value; NormalsToEdges(this.isLeftPaddle); } } public float X { get { return paddlePosition.X; } set { paddlePosition.X = value; } } public float Y { get { return paddlePosition.Y; } set { paddlePosition.Y = value; } } public float Width { get { return (Scale.X == 1f ? (float)paddleSprite.Width : paddleSprite.Width * Scale.X); } } public float Height { get { return ( Scale.Y==1f ? (float)paddleSprite.Height : paddleSprite.Height*Scale.Y ); } } public Texture2D GetSprite { get { return paddleSprite; } } public Rectangle Boundary { get { return new Rectangle((int)paddlePosition.X, (int)paddlePosition.Y, (int)this.Width, (int)this.Height); } } public bool KeyboardEnabled { get { return keybEnabled; } } #endregion private void NormalsToEdges(bool isLeftPaddle) { Normals2Edges = null; Edge = Vector2.Zero; lst.Clear(); for (int i = 0; i < Vertices.Length; i++) { Edge = Vertices[i + 1 == Vertices.Length ? 0 : i + 1] - Vertices[i]; if (Edge != Vector2.Zero) { Edge.Normalize(); //outer normal to edge !! (origin in top-left) lst.Add(new Vector2(Edge.Y, -Edge.X)); } } Normals2Edges = lst.ToArray(); } public float[] ProjectPaddle(Vector2 axis) { if (Vertices.Length == 0 || axis == Vector2.Zero) return (new float[2] { 0, 0 }); float min, max; min = Vector2.Dot(axis, Vertices[0]); max = min; for (int i = 1; i < Vertices.Length; i++) { float p = Vector2.Dot(axis, Vertices[i]); if (p < min) min = p; else if (p > max) max = p; } return (new float[2] { min, max }); } public Paddle(Game game, bool isLeftPaddle, bool enableKeyboard = true) : base(game) { contentManager = new ContentManager(game.Services); keybEnabled = enableKeyboard; this.isLeftPaddle = isLeftPaddle; } public void setPosition(Vector2 newPos) { X = newPos.X; Y = newPos.Y; } public override void Initialize() { base.Initialize(); this.Speed = DEFAULT_Y_SPEED; X = 0; Y = 0; NormalsToEdges(this.isLeftPaddle); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); paddleSprite = contentManager.Load<Texture2D>(@"Content\pongBar"); } public override void Update(GameTime gameTime) { //vertices array Vertices[0] = this.paddlePosition; Vertices[1] = this.paddlePosition + new Vector2(this.Width, 0); Vertices[2] = this.paddlePosition + new Vector2(this.Width, this.Height); Vertices[3] = this.paddlePosition + new Vector2(0, this.Height); // Move paddle, but don't allow movement off the screen if (KeyboardEnabled) { float moveDistance = Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState newKeyState = Keyboard.GetState(); if (newKeyState.IsKeyDown(Keys.Down) && Y + paddleSprite.Height + moveDistance <= Game.GraphicsDevice.Viewport.Height) { Y += moveDistance; } else if (newKeyState.IsKeyDown(Keys.Up) && Y - moveDistance >= 0) { Y -= moveDistance; } } else { if (this.Y + this.Height > this.GraphicsDevice.Viewport.Height) { this.Y = this.Game.GraphicsDevice.Viewport.Height - this.Height - 1; } } base.Update(gameTime); } public override void Draw(GameTime gameTime) { spriteBatch.Begin(SpriteSortMode.Texture,null); spriteBatch.Draw(paddleSprite, paddlePosition, null, Color.White, 0f, Vector2.Zero, Scale, SpriteEffects.None, 0); spriteBatch.End(); base.Draw(gameTime); } } Ball Class public class Ball : Microsoft.Xna.Framework.DrawableGameComponent { #region Private Members private SpriteBatch spriteBatch; private ContentManager contentManager; private const float DEFAULT_SPEED = 50; private float speedIncrement = 0; private Vector2 ballScale = new Vector2(1f, 1f); private const float INCREASE_SPEED = 50; private Texture2D ballSprite; //initial texture private Vector2 ballPosition; //position private Vector2 centerOfBall; //center coords private Vector2 ballSpeed = new Vector2(DEFAULT_SPEED, DEFAULT_SPEED); //speed #endregion #region Properties public float DEFAULTSPEED { get { return DEFAULT_SPEED; } } public Vector2 ballCenter { get { return centerOfBall; } } public Vector2 Scale { get { return ballScale; } set { ballScale = value; } } public float SpeedX { get { return ballSpeed.X; } set { ballSpeed.X = value; } } public float SpeedY { get { return ballSpeed.Y; } set { ballSpeed.Y = value; } } public float X { get { return ballPosition.X; } set { ballPosition.X = value; } } public float Y { get { return ballPosition.Y; } set { ballPosition.Y = value; } } public Texture2D GetSprite { get { return ballSprite; } } public float Width { get { return (Scale.X == 1f ? (float)ballSprite.Width : ballSprite.Width * Scale.X); } } public float Height { get { return (Scale.Y == 1f ? (float)ballSprite.Height : ballSprite.Height * Scale.Y); } } public float SpeedIncreaseIncrement { get { return speedIncrement; } set { speedIncrement = value; } } public Rectangle Boundary { get { return new Rectangle((int)ballPosition.X, (int)ballPosition.Y, (int)this.Width, (int)this.Height); } } #endregion public Ball(Game game) : base(game) { contentManager = new ContentManager(game.Services); } public void Reset() { ballSpeed.X = DEFAULT_SPEED; ballSpeed.Y = DEFAULT_SPEED; ballPosition.X = Game.GraphicsDevice.Viewport.Width / 2 - ballSprite.Width / 2; ballPosition.Y = Game.GraphicsDevice.Viewport.Height / 2 - ballSprite.Height / 2; } public void SpeedUp() { if (ballSpeed.Y < 0) ballSpeed.Y -= (INCREASE_SPEED + speedIncrement); else ballSpeed.Y += (INCREASE_SPEED + speedIncrement); if (ballSpeed.X < 0) ballSpeed.X -= (INCREASE_SPEED + speedIncrement); else ballSpeed.X += (INCREASE_SPEED + speedIncrement); } public float[] ProjectBall(Vector2 axis) { if (axis == Vector2.Zero) return (new float[2] { 0, 0 }); float min, max; min = Vector2.Dot(axis, this.ballCenter) - this.Width/2; //center - radius max = min + this.Width; //center + radius return (new float[2] { min, max }); } public void ChangeHorzDirection() { ballSpeed.X *= -1; } public void ChangeVertDirection() { ballSpeed.Y *= -1; } public override void Initialize() { base.Initialize(); ballPosition.X = Game.GraphicsDevice.Viewport.Width / 2 - ballSprite.Width / 2; ballPosition.Y = Game.GraphicsDevice.Viewport.Height / 2 - ballSprite.Height / 2; } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); ballSprite = contentManager.Load<Texture2D>(@"Content\ball"); } public override void Update(GameTime gameTime) { if (this.Y < 1 || this.Y > GraphicsDevice.Viewport.Height - this.Height - 1) this.ChangeVertDirection(); centerOfBall = new Vector2(ballPosition.X + this.Width / 2, ballPosition.Y + this.Height / 2); base.Update(gameTime); } public override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.Draw(ballSprite, ballPosition, null, Color.White, 0f, Vector2.Zero, Scale, SpriteEffects.None, 0); spriteBatch.End(); base.Draw(gameTime); } } Main game class public class gameStart : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; public gameStart() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; this.Window.Title = "Pong game"; } protected override void Initialize() { ball = new Ball(this); paddleLeft = new Paddle(this,true,false); paddleRight = new Paddle(this,false,true); Components.Add(ball); Components.Add(paddleLeft); Components.Add(paddleRight); this.Window.AllowUserResizing = false; this.IsMouseVisible = true; this.IsFixedTimeStep = false; this.isColliding = false; base.Initialize(); } #region MyPrivateStuff private Ball ball; private Paddle paddleLeft, paddleRight; private int[] bit = { -1, 1 }; private Random rnd = new Random(); private int updates = 0; enum nrPaddle { None, Left, Right }; private nrPaddle PongBar = nrPaddle.None; private ArrayList Axes = new ArrayList(); private Vector2 MTV; //minimum translation vector private bool isColliding; private float overlap; //smallest distance after projections private Vector2 overlapAxis; //axis of overlap #endregion protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); paddleLeft.setPosition(new Vector2(0, this.GraphicsDevice.Viewport.Height / 2 - paddleLeft.Height / 2)); paddleRight.setPosition(new Vector2(this.GraphicsDevice.Viewport.Width - paddleRight.Width, this.GraphicsDevice.Viewport.Height / 2 - paddleRight.Height / 2)); paddleLeft.Scale = new Vector2(1f, 2f); //scale left paddle } private bool ShapesIntersect(Paddle paddle, Ball ball) { overlap = 1000000f; //large value overlapAxis = Vector2.Zero; MTV = Vector2.Zero; foreach (Vector2 ax in Axes) { float[] pad = paddle.ProjectPaddle(ax); //pad0 = min, pad1 = max float[] circle = ball.ProjectBall(ax); //circle0 = min, circle1 = max if (pad[1] <= circle[0] || circle[1] <= pad[0]) { return false; } if (pad[1] - circle[0] < circle[1] - pad[0]) { if (Math.Abs(overlap) > Math.Abs(-pad[1] + circle[0])) { overlap = -pad[1] + circle[0]; overlapAxis = ax; } } else { if (Math.Abs(overlap) > Math.Abs(circle[1] - pad[0])) { overlap = circle[1] - pad[0]; overlapAxis = ax; } } } if (overlapAxis != Vector2.Zero) { MTV = overlapAxis * overlap; } return true; } protected override void Update(GameTime gameTime) { updates += 1; float ftime = 5 * (float)gameTime.ElapsedGameTime.TotalSeconds; if (updates == 1) { isColliding = false; int Xrnd = bit[Convert.ToInt32(rnd.Next(0, 2))]; int Yrnd = bit[Convert.ToInt32(rnd.Next(0, 2))]; ball.SpeedX = Xrnd * ball.SpeedX; ball.SpeedY = Yrnd * ball.SpeedY; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; } else { updates = 100; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; } //autorun :) paddleLeft.Y = ball.Y; //collision detection PongBar = nrPaddle.None; if (ball.Boundary.Intersects(paddleLeft.Boundary)) { PongBar = nrPaddle.Left; if (!isColliding) { Axes.Clear(); Axes.AddRange(paddleLeft.Normal2EdgesVector); //axis from nearest vertex to ball's center Axes.Add(FORMULAS.NormAxisFromCircle2ClosestVertex(paddleLeft.VertexVector, ball.ballCenter)); } } else if (ball.Boundary.Intersects(paddleRight.Boundary)) { PongBar = nrPaddle.Right; if (!isColliding) { Axes.Clear(); Axes.AddRange(paddleRight.Normal2EdgesVector); //axis from nearest vertex to ball's center Axes.Add(FORMULAS.NormAxisFromCircle2ClosestVertex(paddleRight.VertexVector, ball.ballCenter)); } } if (PongBar != nrPaddle.None && !isColliding) switch (PongBar) { case nrPaddle.Left: if (ShapesIntersect(paddleLeft, ball)) { isColliding = true; if (MTV != Vector2.Zero) ball.X += MTV.X; ball.Y += MTV.Y; ball.ChangeHorzDirection(); } break; case nrPaddle.Right: if (ShapesIntersect(paddleRight, ball)) { isColliding = true; if (MTV != Vector2.Zero) ball.X += MTV.X; ball.Y += MTV.Y; ball.ChangeHorzDirection(); } break; default: break; } if (!ShapesIntersect(paddleRight, ball) && !ShapesIntersect(paddleLeft, ball)) isColliding = false; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; //check ball movement if (ball.X > paddleRight.X + paddleRight.Width + 2) { //IncreaseScore(Left); ball.Reset(); updates = 0; return; } else if (ball.X < paddleLeft.X - 2) { //IncreaseScore(Right); ball.Reset(); updates = 0; return; } base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.Aquamarine); spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend); spriteBatch.End(); base.Draw(gameTime); } } And one method i've used: public static Vector2 NormAxisFromCircle2ClosestVertex(Vector2[] vertices, Vector2 circle) { Vector2 temp = Vector2.Zero; if (vertices.Length > 0) { float dist = (circle.X - vertices[0].X) * (circle.X - vertices[0].X) + (circle.Y - vertices[0].Y) * (circle.Y - vertices[0].Y); for (int i = 1; i < vertices.Length;i++) { if (dist > (circle.X - vertices[i].X) * (circle.X - vertices[i].X) + (circle.Y - vertices[i].Y) * (circle.Y - vertices[i].Y)) { temp = vertices[i]; //memorize the closest vertex dist = (circle.X - vertices[i].X) * (circle.X - vertices[i].X) + (circle.Y - vertices[i].Y) * (circle.Y - vertices[i].Y); } } temp = circle - temp; temp.Normalize(); } return temp; } Thanks in advance for any tips on the 4 issues. EDIT1: Something isn't working properly. The collision axis doesn't come out right and the interpolation also seems to have no effect. I've changed the code a bit: private bool ShapesIntersect(Paddle paddle, Ball ball) { overlap = 1000000f; //large value overlapAxis = Vector2.Zero; MTV = Vector2.Zero; foreach (Vector2 ax in Axes) { float[] pad = paddle.ProjectPaddle(ax); //pad0 = min, pad1 = max float[] circle = ball.ProjectBall(ax); //circle0 = min, circle1 = max if (pad[1] < circle[0] || circle[1] < pad[0]) { return false; } if (Math.Abs(pad[1] - circle[0]) < Math.Abs(circle[1] - pad[0])) { if (Math.Abs(overlap) > Math.Abs(-pad[1] + circle[0])) { overlap = -pad[1] + circle[0]; overlapAxis = ax * (-1); } //to get the proper axis } else { if (Math.Abs(overlap) > Math.Abs(circle[1] - pad[0])) { overlap = circle[1] - pad[0]; overlapAxis = ax; } } } if (overlapAxis != Vector2.Zero) { MTV = overlapAxis * Math.Abs(overlap); } return true; } And part of the Update method: if (ShapesIntersect(paddleRight, ball)) { isColliding = true; if (MTV != Vector2.Zero) { ball.X += MTV.X; ball.Y += MTV.Y; } //test if (overlapAxis.X == 0) //collision with horizontal edge { } else if (overlapAxis.Y == 0) //collision with vertical edge { float factor = Math.Abs(ball.ballCenter.Y - paddleRight.Y) / paddleRight.Height; if (factor > 1) factor = 1f; if (overlapAxis.X < 0) //left edge? ball.Speed = ball.DEFAULTSPEED * Vector2.Normalize(Vector2.Reflect(ball.Speed, (Vector2.Lerp(new Vector2(-1, -3), new Vector2(-1, 3), factor)))); else //right edge? ball.Speed = ball.DEFAULTSPEED * Vector2.Normalize(Vector2.Reflect(ball.Speed, (Vector2.Lerp(new Vector2(1, -3), new Vector2(1, 3), factor)))); } else //vertex collision??? { ball.Speed = -ball.Speed; } } What seems to happen is that "overlapAxis" doesn't always return the right one. So instead of (-1,0) i get the (1,0) (this happened even before i multiplied with -1 there). Sometimes there isn't even a collision registered even though the ball passes through the paddle... The interpolation also seems to have no effect as the angles barely change (or the overlapAxis is almost never (-1,0) or (1,0) but something like (0.9783473, 0.02743843)... ). What am i missing here? :(

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  • How to attach turrets to tiles in a tile based game

    - by Joseph St. Pierre
    I am a flash developer, and I am building a Tower Defense game. The world is being built through tiles, and I have gotten that accomplished easily. I have also gotten level changes and enemy spawning down as well. However, I wish the player to be able to spawn turrets, and have those turrets be on specific tiles, based upon where the player placed it. Here is my code: stop(); colOffset = 50; rowOffset = 50; guns = []; placed = true; dead = 0; spawned = 0; level = 1; interval = 350 / level; amount = level * 20; counter = 0; numCol = 14; numRow = 10; tiles = []; k = 0; create = false; tileName = new Array("road","grass","end", "start"); board = new Array( new Array(1,1,1,1,3,1,1,1,1,1,2,1,1,1), new Array(1,1,1,0,0,1,1,1,1,1,0,1,1,1), new Array(1,1,1,0,1,1,1,1,1,1,0,0,1,1), new Array(1,1,1,0,0,0,1,1,1,1,1,0,1,1), new Array(1,1,1,0,1,0,0,0,1,1,1,0,0,1), new Array(1,1,1,0,1,1,1,0,0,1,1,1,0,1), new Array(1,1,0,0,1,1,1,1,0,1,1,0,0,1), new Array(1,1,0,1,1,1,1,1,0,1,0,0,1,1), new Array(1,1,0,0,0,0,0,0,0,1,0,1,1,1), new Array(1,1,1,1,1,1,1,1,0,0,0,1,1,1) ); buildBoard(); function buildBoard(){ for ( col = 0; col < numCol; col++){ for ( row = 0; row < numRow; row++){ _root.attachMovie("tile", "tile_" + col + "_" + row, _root.getNextHighestDepth()); theTile = eval("tile_" + col + "_" + row); theTile._x = (col * 50); theTile._y = (row * 50); theTile.row = row; theTile.col = col; tileType = board[row][col]; theTile.gotoAndStop(tileName[tileType]); tiles.push(theTile); } } } init(); function init(){ onEnterFrame = function(){ counter += 1; if ( spawned < amount && counter > 50){ min= _root.attachMovie("minion","minion",_root.getNextHighestDepth()); min._x = tile_4_0._x + 25; min._y = tile_4_0._y + 25; min.health = 100; choose = Math.round(Math.random()); if ( choose == 0 ){ min.waypointX = [ tile_4_1._x +25, tile_3_1._x + 25, tile_3_2._x + 25, tile_3_6._x + 25, tile_2_6._x + 25, tile_2_8._x + 25, tile_8_8._x + 25, tile_8_9._x + 25, tile_10_9._x + 25, tile_10_7._x + 25, tile_11_7._x + 25, tile_11_6._x + 25, tile_12_6._x + 25, tile_12_4._x + 25, tile_11_4._x + 25, tile_11_2._x + 25, tile_10_2._x + 25, tile_10_0._x + 25]; min.waypointY = [ tile_4_1._y +25, tile_3_1._y + 25, tile_3_2._y + 25, tile_3_6._y + 25, tile_2_6._y + 25, tile_2_8._y + 25, tile_8_8._y + 25, tile_8_9._y + 25, tile_10_9._y + 25, tile_10_7._y + 25, tile_11_7._y + 25, tile_11_6._y + 25, tile_12_6._y + 25, tile_12_4._y + 25, tile_11_4._y + 25, tile_11_2._y + 25, tile_10_2._y + 25, tile_10_0._y + 25]; } else if ( choose == 1 ){ min.waypointX = [ tile_4_1._x +25, tile_3_1._x + 25, tile_3_2._x + 25, tile_3_3._x + 25, tile_5_3._x + 25, tile_5_4._x + 25, tile_7_4._x + 25, tile_7_5._x + 25, tile_8_5._x + 25, tile_8_8._x + 25, tile_8_9._x + 25, tile_10_9._x + 25, tile_10_7._x + 25, tile_11_7._x + 25, tile_11_6._x + 25, tile_12_6._x + 25, tile_12_4._x + 25, tile_11_4._x + 25, tile_11_2._x + 25, tile_10_2._x + 25, tile_10_0._x + 25 ]; min.waypointY = [ tile_4_1._y +25, tile_3_1._y + 25, tile_3_2._y + 25, tile_3_3._y + 25, tile_5_3._y + 25, tile_5_4._y + 25, tile_7_4._y + 25, tile_7_5._y + 25, tile_8_5._y + 25, tile_8_8._y + 25, tile_8_9._y + 25, tile_10_9._y + 25, tile_10_7._y + 25, tile_11_7._y + 25, tile_11_6._y + 25, tile_12_6._y + 25, tile_12_4._y + 25, tile_11_4._y + 25, tile_11_2._y + 25, tile_10_2._y + 25, tile_10_0._y + 25 ]; } min.i = 0; counter = 0; spawned += 1; min.onEnterFrame = function(){ dx = this.waypointX[this.i] - this._x; dy = this.waypointY[this.i] - this._y; radians = Math.atan2(dy,dx); degrees = radians * 180 / Math.PI; xspeed = Math.cos(radians); yspeed = Math.sin(radians); this._x += xspeed; this._y += yspeed; if( this._x == this.waypointX[this.i] && this._y == this.waypointY[this.i]){ this.i++; } if ( this._x == tile_10_0._x + 25 && this._y == tile_10_0._y + 25){ this.removeMovieClip(); dead += 1; } } } if ( dead >= amount ){ dead = 0; level += 1; amount = level * 20; spawned = 0; } } btnM.onRelease = function(){ create = true; } } game.onEnterFrame = function(){ } It is possible for me however to complete this task, but only once. I am able to make the turret, drag it over to a tile, and have it attach itself to the tile. No problem. The issue is, I cannot do these multiple times. Please Help.

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  • What is the most efficiant way to get the highest and the lowest value in a Array

    - by meo
    is there something like PHP: max() in javascript? lets say i have an array like this: [2, 3, 23, 2, 2345, 4, 86, 8, 231, 75] and i want to return the highest and the lowest value in this array. What is the fastest way to do that? i have tried: function madmax (arr) { var max = arr[0], min = arr[1] if (min > max) { max = arr[1] min = arr[0] } for (i=1;i<=arr.length;i++){ if( arr[i] > max ) { max = arr[i] }else if( arr[i] < min ) { min = arr[i] } } return max, min } madmax([123, 2, 345, 153, 5, 98, 456, 4323456, 1, 234, 19874, 238, 4]) Is there a simpler way retrieve the max and min value of a array?

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  • What is the most efficient way to get the highest and the lowest values in a Array

    - by meo
    is there something like PHP: max() in javascript? lets say i have an array like this: [2, 3, 23, 2, 2345, 4, 86, 8, 231, 75] and i want to return the highest and the lowest value in this array. What is the fastest way to do that? i have tried: function madmax (arr) { var max = arr[0], min = arr[1] if (min > max) { max = arr[1] min = arr[0] } for (i=1;i<=arr.length;i++){ if( arr[i] > max ) { max = arr[i] }else if( arr[i] < min ) { min = arr[i] } } return max, min } madmax([123, 2, 345, 153, 5, 98, 456, 4323456, 1, 234, 19874, 238, 4]) Is there a simpler way retrieve the max and min value of a array?

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  • How to tune down the Hyperic built-in postgresql database for a small setup

    - by Svish
    We are testing out Hyperic 4.5.1 in a quite small environment for now. Currently there are just 1-5 agents and there probably won't be any more than 10-15. When I run ps ax there are 20(!) postgres processes running. For a small setup like this, that can't be necessary, can it? I'm a software developer and don't have much experience with setting up servers and such though, so don't really know. Either way, what settings are appropriate for a small Hyperic setup like this? Current, default and untouched configuration file, hqdb/data/postgresql.conf: # ----------------------------- # PostgreSQL configuration file # ----------------------------- # # This file consists of lines of the form: # # name = value # # (The '=' is optional.) White space may be used. Comments are introduced # with '#' anywhere on a line. The complete list of option names and # allowed values can be found in the PostgreSQL documentation. The # commented-out settings shown in this file represent the default values. # # Please note that re-commenting a setting is NOT sufficient to revert it # to the default value, unless you restart the server. # # Any option can also be given as a command line switch to the server, # e.g., 'postgres -c log_connections=on'. Some options can be changed at # run-time with the 'SET' SQL command. # # This file is read on server startup and when the server receives a # SIGHUP. If you edit the file on a running system, you have to SIGHUP the # server for the changes to take effect, or use "pg_ctl reload". Some # settings, which are marked below, require a server shutdown and restart # to take effect. # # Memory units: kB = kilobytes MB = megabytes GB = gigabytes # Time units: ms = milliseconds s = seconds min = minutes h = hours d = days #--------------------------------------------------------------------------- # FILE LOCATIONS #--------------------------------------------------------------------------- # The default values of these variables are driven from the -D command line # switch or PGDATA environment variable, represented here as ConfigDir. #data_directory = 'ConfigDir' # use data in another directory # (change requires restart) #hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file # (change requires restart) #ident_file = 'ConfigDir/pg_ident.conf' # ident configuration file # (change requires restart) # If external_pid_file is not explicitly set, no extra PID file is written. #external_pid_file = '(none)' # write an extra PID file # (change requires restart) #--------------------------------------------------------------------------- # CONNECTIONS AND AUTHENTICATION #--------------------------------------------------------------------------- # - Connection Settings - #listen_addresses = 'localhost' # what IP address(es) to listen on; # comma-separated list of addresses; # defaults to 'localhost', '*' = all # (change requires restart) port = 9432 # (change requires restart) max_connections = 100 # (change requires restart) # Note: increasing max_connections costs ~400 bytes of shared memory per # connection slot, plus lock space (see max_locks_per_transaction). You # might also need to raise shared_buffers to support more connections. #superuser_reserved_connections = 3 # (change requires restart) #unix_socket_directory = '' # (change requires restart) #unix_socket_group = '' # (change requires restart) #unix_socket_permissions = 0777 # octal # (change requires restart) #bonjour_name = '' # defaults to the computer name # (change requires restart) # - Security & Authentication - #authentication_timeout = 1min # 1s-600s #ssl = off # (change requires restart) #password_encryption = on #db_user_namespace = off # Kerberos #krb_server_keyfile = '' # (change requires restart) #krb_srvname = 'postgres' # (change requires restart) #krb_server_hostname = '' # empty string matches any keytab entry # (change requires restart) #krb_caseins_users = off # (change requires restart) # - TCP Keepalives - # see 'man 7 tcp' for details #tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds; # 0 selects the system default #tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds; # 0 selects the system default #tcp_keepalives_count = 0 # TCP_KEEPCNT; # 0 selects the system default #--------------------------------------------------------------------------- # RESOURCE USAGE (except WAL) #--------------------------------------------------------------------------- # - Memory - shared_buffers = 64MB # min 128kB or max_connections*16kB # (change requires restart) #temp_buffers = 8MB # min 800kB #max_prepared_transactions = 5 # can be 0 or more # (change requires restart) # Note: increasing max_prepared_transactions costs ~600 bytes of shared memory # per transaction slot, plus lock space (see max_locks_per_transaction). work_mem = 2MB # min 64kB maintenance_work_mem = 32MB # min 1MB #max_stack_depth = 2MB # min 100kB # - Free Space Map - max_fsm_pages = 204800 # min max_fsm_relations*16, 6 bytes each # (change requires restart) #max_fsm_relations = 1000 # min 100, ~70 bytes each # (change requires restart) # - Kernel Resource Usage - #max_files_per_process = 1000 # min 25 # (change requires restart) #shared_preload_libraries = '' # (change requires restart) # - Cost-Based Vacuum Delay - #vacuum_cost_delay = 0 # 0-1000 milliseconds #vacuum_cost_page_hit = 1 # 0-10000 credits #vacuum_cost_page_miss = 10 # 0-10000 credits #vacuum_cost_page_dirty = 20 # 0-10000 credits #vacuum_cost_limit = 200 # 0-10000 credits # - Background writer - #bgwriter_delay = 200ms # 10-10000ms between rounds #bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers scanned/round #bgwriter_lru_maxpages = 5 # 0-1000 buffers max written/round #bgwriter_all_percent = 0.333 # 0-100% of all buffers scanned/round #bgwriter_all_maxpages = 5 # 0-1000 buffers max written/round #--------------------------------------------------------------------------- # WRITE AHEAD LOG #--------------------------------------------------------------------------- # - Settings - fsync = on # turns forced synchronization on or off #wal_sync_method = fsync # the default is the first option # supported by the operating system: # open_datasync # fdatasync # fsync # fsync_writethrough # open_sync #full_page_writes = on # recover from partial page writes #wal_buffers = 64kB # min 32kB # (change requires restart) commit_delay = 100000 # range 0-100000, in microseconds #commit_siblings = 5 # range 1-1000 # - Checkpoints - checkpoint_segments = 10 # in logfile segments, min 1, 16MB each #checkpoint_timeout = 5min # range 30s-1h #checkpoint_warning = 30s # 0 is off # - Archiving - #archive_command = '' # command to use to archive a logfile segment #archive_timeout = 0 # force a logfile segment switch after this # many seconds; 0 is off #--------------------------------------------------------------------------- # QUERY TUNING #--------------------------------------------------------------------------- # - Planner Method Configuration - #enable_bitmapscan = on #enable_hashagg = on #enable_hashjoin = on #enable_indexscan = on #enable_mergejoin = on #enable_nestloop = on #enable_seqscan = on #enable_sort = on #enable_tidscan = on # - Planner Cost Constants - #seq_page_cost = 1.0 # measured on an arbitrary scale #random_page_cost = 4.0 # same scale as above #cpu_tuple_cost = 0.01 # same scale as above #cpu_index_tuple_cost = 0.005 # same scale as above #cpu_operator_cost = 0.0025 # same scale as above #effective_cache_size = 128MB # - Genetic Query Optimizer - #geqo = on #geqo_threshold = 12 #geqo_effort = 5 # range 1-10 #geqo_pool_size = 0 # selects default based on effort #geqo_generations = 0 # selects default based on effort #geqo_selection_bias = 2.0 # range 1.5-2.0 # - Other Planner Options - #default_statistics_target = 10 # range 1-1000 #constraint_exclusion = off #from_collapse_limit = 8 #join_collapse_limit = 8 # 1 disables collapsing of explicit # JOINs #--------------------------------------------------------------------------- # ERROR REPORTING AND LOGGING #--------------------------------------------------------------------------- # - Where to Log - log_destination = 'stderr' # Valid values are combinations of # stderr, syslog and eventlog, # depending on platform. # This is used when logging to stderr: redirect_stderr = on # Enable capturing of stderr into log # files # (change requires restart) # These are only used if redirect_stderr is on: log_directory = '../../logs' # Directory where log files are written # Can be absolute or relative to PGDATA log_filename = 'hqdb-%Y-%m-%d.log' # Log file name pattern. # Can include strftime() escapes #log_truncate_on_rotation = off # If on, any existing log file of the same # name as the new log file will be # truncated rather than appended to. But # such truncation only occurs on # time-driven rotation, not on restarts # or size-driven rotation. Default is # off, meaning append to existing files # in all cases. log_rotation_age = 1d # Automatic rotation of logfiles will # happen after that time. 0 to # disable. #log_rotation_size = 10MB # Automatic rotation of logfiles will # happen after that much log # output. 0 to disable. # These are relevant when logging to syslog: #syslog_facility = 'LOCAL0' #syslog_ident = 'postgres' # - When to Log - #client_min_messages = notice # Values, in order of decreasing detail: # debug5 # debug4 # debug3 # debug2 # debug1 # log # notice # warning # error #log_min_messages = notice # Values, in order of decreasing detail: # debug5 # debug4 # debug3 # debug2 # debug1 # info # notice # warning # error # log # fatal # panic #log_error_verbosity = default # terse, default, or verbose messages #log_min_error_statement = error # Values in order of increasing severity: # debug5 # debug4 # debug3 # debug2 # debug1 # info # notice # warning # error # fatal # panic (effectively off) log_min_duration_statement = 10000 # -1 is disabled, 0 logs all statements # and their durations. #silent_mode = off # DO NOT USE without syslog or # redirect_stderr # (change requires restart) # - What to Log - #debug_print_parse = off #debug_print_rewritten = off #debug_print_plan = off #debug_pretty_print = off #log_connections = off #log_disconnections = off #log_duration = off #log_line_prefix = '' # Special values: # %u = user name # %d = database name # %r = remote host and port # %h = remote host # %p = PID # %t = timestamp (no milliseconds) # %m = timestamp with milliseconds # %i = command tag # %c = session id # %l = session line number # %s = session start timestamp # %x = transaction id # %q = stop here in non-session # processes # %% = '%' # e.g. '<%u%%%d> ' #log_statement = 'none' # none, ddl, mod, all #log_hostname = off #--------------------------------------------------------------------------- # RUNTIME STATISTICS #--------------------------------------------------------------------------- # - Query/Index Statistics Collector - #stats_command_string = on #update_process_title = on stats_start_collector = on # needed for block or row stats # (change requires restart) stats_block_level = on stats_row_level = on stats_reset_on_server_start = off # (change requires restart) # - Statistics Monitoring - #log_parser_stats = off #log_planner_stats = off #log_executor_stats = off #log_statement_stats = off #--------------------------------------------------------------------------- # AUTOVACUUM PARAMETERS #--------------------------------------------------------------------------- #autovacuum = off # enable autovacuum subprocess? # 'on' requires stats_start_collector # and stats_row_level to also be on #autovacuum_naptime = 1min # time between autovacuum runs #autovacuum_vacuum_threshold = 500 # min # of tuple updates before # vacuum #autovacuum_analyze_threshold = 250 # min # of tuple updates before # analyze #autovacuum_vacuum_scale_factor = 0.2 # fraction of rel size before # vacuum #autovacuum_analyze_scale_factor = 0.1 # fraction of rel size before # analyze #autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum # (change requires restart) #autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for # autovacuum, -1 means use # vacuum_cost_delay #autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for # autovacuum, -1 means use # vacuum_cost_limit #--------------------------------------------------------------------------- # CLIENT CONNECTION DEFAULTS #--------------------------------------------------------------------------- # - Statement Behavior - #search_path = '"$user",public' # schema names #default_tablespace = '' # a tablespace name, '' uses # the default #check_function_bodies = on #default_transaction_isolation = 'read committed' #default_transaction_read_only = off #statement_timeout = 0 # 0 is disabled #vacuum_freeze_min_age = 100000000 # - Locale and Formatting - datestyle = 'iso, mdy' #timezone = unknown # actually, defaults to TZ # environment setting #timezone_abbreviations = 'Default' # select the set of available timezone # abbreviations. Currently, there are # Default # Australia # India # However you can also create your own # file in share/timezonesets/. #extra_float_digits = 0 # min -15, max 2 #client_encoding = sql_ascii # actually, defaults to database # encoding # These settings are initialized by initdb -- they might be changed lc_messages = 'C' # locale for system error message # strings lc_monetary = 'C' # locale for monetary formatting lc_numeric = 'C' # locale for number formatting lc_time = 'C' # locale for time formatting # - Other Defaults - #explain_pretty_print = on #dynamic_library_path = '$libdir' #local_preload_libraries = '' #--------------------------------------------------------------------------- # LOCK MANAGEMENT #--------------------------------------------------------------------------- #deadlock_timeout = 1s #max_locks_per_transaction = 64 # min 10 # (change requires restart) # Note: each lock table slot uses ~270 bytes of shared memory, and there are # max_locks_per_transaction * (max_connections + max_prepared_transactions) # lock table slots. #--------------------------------------------------------------------------- # VERSION/PLATFORM COMPATIBILITY #--------------------------------------------------------------------------- # - Previous Postgres Versions - #add_missing_from = off #array_nulls = on #backslash_quote = safe_encoding # on, off, or safe_encoding #default_with_oids = off #escape_string_warning = on #standard_conforming_strings = off #regex_flavor = advanced # advanced, extended, or basic #sql_inheritance = on # - Other Platforms & Clients - #transform_null_equals = off #--------------------------------------------------------------------------- # CUSTOMIZED OPTIONS #--------------------------------------------------------------------------- #custom_variable_classes = '' # list of custom variable class names SELECT * FROM pg_stat_activity; datid | datname | procpid | usesysid | usename | current_query | waiting | query_start | backend_start | client_addr | client_port -------+---------+---------+----------+---------+---------------------------------+---------+-------------------------------+-------------------------------+-------------+------------- 16384 | hqdb | 3267 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.036781+01 | 2011-02-08 15:51:20.02413+01 | 127.0.0.1 | 47892 16384 | hqdb | 3268 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.050994+01 | 2011-02-08 15:51:20.047393+01 | 127.0.0.1 | 47893 16384 | hqdb | 3269 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.056661+01 | 2011-02-08 15:51:20.053201+01 | 127.0.0.1 | 47894 16384 | hqdb | 3271 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.062351+01 | 2011-02-08 15:51:20.058822+01 | 127.0.0.1 | 47895 16384 | hqdb | 3272 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.068328+01 | 2011-02-08 15:51:20.064517+01 | 127.0.0.1 | 47896 16384 | hqdb | 3273 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.07444+01 | 2011-02-08 15:51:20.070755+01 | 127.0.0.1 | 47897 16384 | hqdb | 3274 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.080941+01 | 2011-02-08 15:51:20.076983+01 | 127.0.0.1 | 47898 16384 | hqdb | 3275 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.08741+01 | 2011-02-08 15:51:20.083697+01 | 127.0.0.1 | 47899 16384 | hqdb | 3276 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:20.093597+01 | 2011-02-08 15:51:20.089977+01 | 127.0.0.1 | 47900 16384 | hqdb | 3277 | 10 | hqadmin | <IDLE> in transaction | f | 2011-02-08 15:51:20.133974+01 | 2011-02-08 15:51:20.096149+01 | 127.0.0.1 | 47901 16384 | hqdb | 3308 | 10 | hqadmin | <IDLE> | f | 2011-02-09 10:49:27.402197+01 | 2011-02-08 15:51:29.826321+01 | 127.0.0.1 | 47902 16384 | hqdb | 3309 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:55.572395+01 | 2011-02-08 15:51:29.865243+01 | 127.0.0.1 | 47903 16384 | hqdb | 3310 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:55.586273+01 | 2011-02-08 15:51:29.874346+01 | 127.0.0.1 | 47904 16384 | hqdb | 3311 | 10 | hqadmin | <IDLE> | f | 2011-02-09 10:10:03.024088+01 | 2011-02-08 15:51:29.883598+01 | 127.0.0.1 | 47905 16384 | hqdb | 3312 | 10 | hqadmin | <IDLE> in transaction | f | 2011-02-08 15:51:35.804457+01 | 2011-02-08 15:51:29.892925+01 | 127.0.0.1 | 47906 16384 | hqdb | 3418 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:55.580207+01 | 2011-02-08 15:51:55.56911+01 | 127.0.0.1 | 47910 16384 | hqdb | 3419 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:55.59781+01 | 2011-02-08 15:51:55.588609+01 | 127.0.0.1 | 47911 16384 | hqdb | 3422 | 10 | hqadmin | <IDLE> | f | 2011-02-09 10:10:02.668836+01 | 2011-02-08 15:51:55.603076+01 | 127.0.0.1 | 47914 16384 | hqdb | 3421 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:55.770427+01 | 2011-02-08 15:51:55.603086+01 | 127.0.0.1 | 47913 16384 | hqdb | 3420 | 10 | hqadmin | <IDLE> | f | 2011-02-08 15:51:55.680785+01 | 2011-02-08 15:51:55.637058+01 | 127.0.0.1 | 47912 16384 | hqdb | 18233 | 10 | hqadmin | SELECT * FROM pg_stat_activity; | f | 2011-02-09 10:49:29.688949+01 | 2011-02-09 10:48:13.031475+01 | | -1 (21 rows)

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  • Postfix configuration - Uing virtual min but server is bouncing back my mail.

    - by brodiebrodie
    I have no experience in setting up postfix, and thought virtualmin minght do the legwork for me. Appears not. When I try to send mail to the domain (either [email protected] [email protected] or [email protected]) I get the following message returned This is the mail system at host dedq239.localdomain. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to <postmaster> If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system <[email protected]> (expanded from <[email protected]>): User unknown in virtual alias table Final-Recipient: rfc822; [email protected] Original-Recipient: rfc822;[email protected] Action: failed Status: 5.0.0 Diagnostic-Code: X-Postfix; User unknown in virtual alias table How can I diagnose the problem here? It seems that the mail gets to my server but the server fails to locally deliver the message to the correct user. (This is a guess, truthfully I have no idea what is happening). I have checked my virtual alias table and it seems to be set up correctly (I can post if this would be helpful). Can anyone give me a clue as to the next step? Thanks alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases broken_sasl_auth_clients = yes command_directory = /usr/sbin config_directory = /etc/postfix daemon_directory = /usr/libexec/postfix debug_peer_level = 2 html_directory = no local_recipient_maps = $virtual_mailbox_maps mailq_path = /usr/bin/mailq.postfix manpage_directory = /usr/share/man mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain myorigin = $mydomain newaliases_path = /usr/bin/newaliases.postfix readme_directory = /usr/share/doc/postfix-2.3.3/README_FILES sample_directory = /usr/share/doc/postfix-2.3.3/samples sendmail_path = /usr/sbin/sendmail.postfix setgid_group = postdrop smtpd_recipient_restrictions = permit_mynetworks reject_unauth_destination smtpd_sasl_auth_enable = yes soft_bounce = no unknown_local_recipient_reject_code = 550 virtual_alias_maps = hash:/etc/postfix/virtual My mail log file (the last entry) Sep 30 15:13:47 dedq239 postfix/cleanup[7237]: 207C6B18158: message-id=<[email protected]> Sep 30 15:13:47 dedq239 postfix/qmgr[7177]: 207C6B18158: from=<[email protected]>, size=1805, nrcpt=1 (queue active) Sep 30 15:13:47 dedq239 postfix/error[7238]: 207C6B18158: to=<[email protected]>, orig_to=<[email protected]>, relay=none, delay=0.64, delays=0.61/0.01/0/0.02, dsn=5.0.0, status=bounced (User unknown in virtual alias table) Sep 30 15:13:47 dedq239 postfix/cleanup[7237]: 8DC13B18169: message-id=<[email protected]> Sep 30 15:13:47 dedq239 postfix/qmgr[7177]: 8DC13B18169: from=<>, size=3691, nrcpt=1 (queue active) Sep 30 15:13:47 dedq239 postfix/bounce[7239]: 207C6B18158: sender non-delivery notification: 8DC13B18169 Sep 30 15:13:47 dedq239 postfix/qmgr[7177]: 207C6B18158: removed Sep 30 15:13:48 dedq239 postfix/smtp[7240]: 8DC13B18169: to=<[email protected]>, relay=gmail-smtp-in.l.google.com[209.85.216.55]:25, delay=1.3, delays=0.02/0.01/0.58/0.75, dsn=2.0.0, status=sent (250 2.0.0 OK 1254348828 36si15082901pxi.91) Sep 30 15:13:48 dedq239 postfix/qmgr[7177]: 8DC13B18169: removed Sep 30 15:14:17 dedq239 postfix/smtpd[7233]: disconnect from mail-bw0-f228.google.com[209.85.218.228] etc.aliases file below I have not touched this file - myvirtualdomain is a replacement for my real domain name # Aliases in this file will NOT be expanded in the header from # Mail, but WILL be visible over networks or from /bin/mail. # # >>>>>>>>>> The program "newaliases" must be run after # >> NOTE >> this file is updated for any changes to # >>>>>>>>>> show through to sendmail. # # Basic system aliases -- these MUST be present. mailer-daemon: postmaster postmaster: root # General redirections for pseudo accounts. bin: root daemon: root adm: root lp: root sync: root shutdown: root halt: root mail: root news: root uucp: root operator: root games: root gopher: root ftp: root nobody: root radiusd: root nut: root dbus: root vcsa: root canna: root wnn: root rpm: root nscd: root pcap: root apache: root webalizer: root dovecot: root fax: root quagga: root radvd: root pvm: root amanda: root privoxy: root ident: root named: root xfs: root gdm: root mailnull: root postgres: root sshd: root smmsp: root postfix: root netdump: root ldap: root squid: root ntp: root mysql: root desktop: root rpcuser: root rpc: root nfsnobody: root ingres: root system: root toor: root manager: root dumper: root abuse: root newsadm: news newsadmin: news usenet: news ftpadm: ftp ftpadmin: ftp ftp-adm: ftp ftp-admin: ftp www: webmaster webmaster: root noc: root security: root hostmaster: root info: postmaster marketing: postmaster sales: postmaster support: postmaster # trap decode to catch security attacks decode: root # Person who should get root's mail #root: marc abuse-myvirtualdomain.com: [email protected] My etc/postfix/virtual file is below - again myvirtualdomain is a replacement. I think this file was generated by Virtualmin and I have tried messing around with is with no success... This is the version without my changes. myunixusername@myvirtualdomain .com myunixusername myvirtualdomain .com myvirtualdomain.com [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]

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  • How to change x-axis min/max of Column chart in Excel?

    - by Ian Boyd
    Here i have a column chart of binomial distribution, showing how many times you can expect to roll a six in 235 dice rolls: Note: You could also call it a binomial mass distribution for p=1/6, n=235 Now that graph is kinda squooshed. i'd like to change the Minimum and Maximum on the horizontal axis. i'd like to change them to: Minimum: 22 Maximum: 57 Meaning i want to zoom in on this section of the graph: Bonus points to the reader who can say how the numbers 22 and 57 were arrived at If this were a Scatter graph in Excel, i could adjust the horizintal axis minimum and maximum as i desired: Unfortunately, this is a Column chart, where there are no options to adjust the minimum and maximum limits of the ordinate axis: i can do a pretty horrible thing to the graph in Photoshop, but it's not very useful afterwards: Question: how to a change the x-axis minimum and maximum of a Column chart in Excel (2007)?

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  • Parallelism in .NET – Part 7, Some Differences between PLINQ and LINQ to Objects

    - by Reed
    In my previous post on Declarative Data Parallelism, I mentioned that PLINQ extends LINQ to Objects to support parallel operations.  Although nearly all of the same operations are supported, there are some differences between PLINQ and LINQ to Objects.  By introducing Parallelism to our declarative model, we add some extra complexity.  This, in turn, adds some extra requirements that must be addressed. In order to illustrate the main differences, and why they exist, let’s begin by discussing some differences in how the two technologies operate, and look at the underlying types involved in LINQ to Objects and PLINQ . LINQ to Objects is mainly built upon a single class: Enumerable.  The Enumerable class is a static class that defines a large set of extension methods, nearly all of which work upon an IEnumerable<T>.  Many of these methods return a new IEnumerable<T>, allowing the methods to be chained together into a fluent style interface.  This is what allows us to write statements that chain together, and lead to the nice declarative programming model of LINQ: double min = collection .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .Min(item => item.PerformComputation()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Other LINQ variants work in a similar fashion.  For example, most data-oriented LINQ providers are built upon an implementation of IQueryable<T>, which allows the database provider to turn a LINQ statement into an underlying SQL query, to be performed directly on the remote database. PLINQ is similar, but instead of being built upon the Enumerable class, most of PLINQ is built upon a new static class: ParallelEnumerable.  When using PLINQ, you typically begin with any collection which implements IEnumerable<T>, and convert it to a new type using an extension method defined on ParallelEnumerable: AsParallel().  This method takes any IEnumerable<T>, and converts it into a ParallelQuery<T>, the core class for PLINQ.  There is a similar ParallelQuery class for working with non-generic IEnumerable implementations. This brings us to our first subtle, but important difference between PLINQ and LINQ – PLINQ always works upon specific types, which must be explicitly created. Typically, the type you’ll use with PLINQ is ParallelQuery<T>, but it can sometimes be a ParallelQuery or an OrderedParallelQuery<T>.  Instead of dealing with an interface, implemented by an unknown class, we’re dealing with a specific class type.  This works seamlessly from a usage standpoint – ParallelQuery<T> implements IEnumerable<T>, so you can always “switch back” to an IEnumerable<T>.  The difference only arises at the beginning of our parallelization.  When we’re using LINQ, and we want to process a normal collection via PLINQ, we need to explicitly convert the collection into a ParallelQuery<T> by calling AsParallel().  There is an important consideration here – AsParallel() does not need to be called on your specific collection, but rather any IEnumerable<T>.  This allows you to place it anywhere in the chain of methods involved in a LINQ statement, not just at the beginning.  This can be useful if you have an operation which will not parallelize well or is not thread safe.  For example, the following is perfectly valid, and similar to our previous examples: double min = collection .AsParallel() .Select(item => item.SomeOperation()) .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .Min(item => item.PerformComputation()); However, if SomeOperation() is not thread safe, we could just as easily do: double min = collection .Select(item => item.SomeOperation()) .AsParallel() .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .Min(item => item.PerformComputation()); In this case, we’re using standard LINQ to Objects for the Select(…) method, then converting the results of that map routine to a ParallelQuery<T>, and processing our filter (the Where method) and our aggregation (the Min method) in parallel. PLINQ also provides us with a way to convert a ParallelQuery<T> back into a standard IEnumerable<T>, forcing sequential processing via standard LINQ to Objects.  If SomeOperation() was thread-safe, but PerformComputation() was not thread-safe, we would need to handle this by using the AsEnumerable() method: double min = collection .AsParallel() .Select(item => item.SomeOperation()) .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .AsEnumerable() .Min(item => item.PerformComputation()); Here, we’re converting our collection into a ParallelQuery<T>, doing our map operation (the Select(…) method) and our filtering in parallel, then converting the collection back into a standard IEnumerable<T>, which causes our aggregation via Min() to be performed sequentially. This could also be written as two statements, as well, which would allow us to use the language integrated syntax for the first portion: var tempCollection = from item in collection.AsParallel() let e = item.SomeOperation() where (e.SomeProperty > 6 && e.SomeProperty < 24) select e; double min = tempCollection.AsEnumerable().Min(item => item.PerformComputation()); This allows us to use the standard LINQ style language integrated query syntax, but control whether it’s performed in parallel or serial by adding AsParallel() and AsEnumerable() appropriately. The second important difference between PLINQ and LINQ deals with order preservation.  PLINQ, by default, does not preserve the order of of source collection. This is by design.  In order to process a collection in parallel, the system needs to naturally deal with multiple elements at the same time.  Maintaining the original ordering of the sequence adds overhead, which is, in many cases, unnecessary.  Therefore, by default, the system is allowed to completely change the order of your sequence during processing.  If you are doing a standard query operation, this is usually not an issue.  However, there are times when keeping a specific ordering in place is important.  If this is required, you can explicitly request the ordering be preserved throughout all operations done on a ParallelQuery<T> by using the AsOrdered() extension method.  This will cause our sequence ordering to be preserved. For example, suppose we wanted to take a collection, perform an expensive operation which converts it to a new type, and display the first 100 elements.  In LINQ to Objects, our code might look something like: // Using IEnumerable<SourceClass> collection IEnumerable<ResultClass> results = collection .Select(e => e.CreateResult()) .Take(100); If we just converted this to a parallel query naively, like so: IEnumerable<ResultClass> results = collection .AsParallel() .Select(e => e.CreateResult()) .Take(100); We could very easily get a very different, and non-reproducable, set of results, since the ordering of elements in the input collection is not preserved.  To get the same results as our original query, we need to use: IEnumerable<ResultClass> results = collection .AsParallel() .AsOrdered() .Select(e => e.CreateResult()) .Take(100); This requests that PLINQ process our sequence in a way that verifies that our resulting collection is ordered as if it were processed serially.  This will cause our query to run slower, since there is overhead involved in maintaining the ordering.  However, in this case, it is required, since the ordering is required for correctness. PLINQ is incredibly useful.  It allows us to easily take nearly any LINQ to Objects query and run it in parallel, using the same methods and syntax we’ve used previously.  There are some important differences in operation that must be considered, however – it is not a free pass to parallelize everything.  When using PLINQ in order to parallelize your routines declaratively, the same guideline I mentioned before still applies: Parallelization is something that should be handled with care and forethought, added by design, and not just introduced casually.

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  • Getting minimum - Min() - for DateTime column in a DataTable using LINQ to DataSets?

    - by Jay Stevens
    I need to get the minimum DateTime value of a column in a DataTable. The DataTable is generated dynamically from a CSV file, therefore I don't know the name of that column until runtime. Here is code I've got that doesn't work... private DateTime GetStartDateFromCSV(string inputFile, string date_attr) { EnumerableRowCollection<DataRow> table = CsvStreamReader.GetDataTableFromCSV(inputFile, "input", true).AsEnumerable(); DateTime dt = table.Select(record => record.Field<DateTime>(date_attr)).Min(); return dt; } The variable table is broken out just for clarity. I basically need to find the minimum value as a DateTime for one of the columns (to be chosen at runtime and represented by date_attr). I have tried several solutions from SO (most deal with known columns and/or non-DateTime fields). What I've got throws an error at runtime telling me that it can't do the DateTime conversion (that seems to be a problem with Linq?) I've confirmed that the data for the column name that is in the string date_attr is a date value.

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