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  • When using Direct3D, how much math is being done on the CPU?

    - by zirgen
    Context: I'm just starting out. I'm not even touching the Direct3D 11 API, and instead looking at understanding the pipeline, etc. From looking at documentation and information floating around the web, it seems like some calculations are being handled by the application. That, is, instead of simply presenting matrices to multiply to the GPU, the calculations are being done by a math library that operates on the CPU. I don't have any particular resources to point to, although I guess I can point to the XNA Math Library or the samples shipped in the February DX SDK. When you see code like mViewProj = mView * mProj;, that projection is being calculated on the CPU. Or am I wrong? If you were writing a program, where you can have 10 cubes on the screen, where you can move or rotate cubes, as well as viewpoint, what calculations would you do on the CPU? I think I would store the geometry for the a single cube, and then transform matrices representing the actual instances. And then it seems I would use the XNA math library, or another of my choosing, to transform each cube in model space. Then get the coordinates in world space. Then push the information to the GPU. That's quite a bit of calculation on the CPU. Am I wrong? Am I reaching conclusions based on too little information and understanding? What terms should I Google for, if the answer is STFW? Or if I am right, why aren't these calculations being pushed to the GPU as well?

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  • How to use a TFileStream to read 2D matrices into dynamic array?

    - by Robert Frank
    I need to read a large (2000x2000) matrix of binary data from a file into a dynamic array with Delphi 2010. I don't know the dimensions until run-time. I've never read raw data like this, and don't know IEEE so I'm posting this to see if I'm on track. I plan to use a TFileStream to read one row at a time. I need to be able to read as many of these formats as possible: 16-bit two's complement binary integer 32-bit two's complement binary integer 64-bit two's complement binary integer IEEE single precision floating-point For 32-bit two's complement, I'm thinking something like the code below. Changing to Int64 and Int16 should be straight forward. How can I read the IEEE? Am I on the right track? Any suggestions on this code, or how to elegantly extend it for all 4 data types above? Since my post-processing will be the same after reading this data, I guess I'll have to copy the matrix into a common format when done. I have no problem just having four procedures (one for each data type) like the one below, but perhaps there's an elegant way to use RTTI or buffers and then move()'s so that the same code works for all 4 datatypes? Thanks! type TRowData = array of Int32; procedure ReadMatrix; var Matrix: array of TRowData; NumberOfRows: Cardinal; NumberOfCols: Cardinal; CurRow: Integer; begin NumberOfRows := 20; // not known until run time NumberOfCols := 100; // not known until run time SetLength(Matrix, NumberOfRows); for CurRow := 0 to NumberOfRows do begin SetLength(Matrix[CurRow], NumberOfCols); FileStream.ReadBuffer(Matrix[CurRow], NumberOfCols * SizeOf(Int32)) ); end; end;

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  • Why is my Android app force closing when I try to check if an EditText has a double

    - by user336861
    Scanner scanner = new Scanner(lapsPerMile_st); if (!scanner.hasNextDouble()) { Context context = getApplicationContext(); String msg = "Please Enter Digits and Decmials Only"; int duration = Toast.LENGTH_LONG; Toast.makeText(context, msg, duration).show(); lapsPerMileEditText.setText(""); return; } else { //Edit box has only digits, Set data and display stats data.setLapsPerMile(Integer.parseInt(lapsPerMile_st)); lapsRunLabel.setVisibility(0); lapsRunTextView.setText(Integer.toString(data.getLapsRun())); milesRunLabel.setVisibility(0); milesRunTextView.setText(Double.toString(data.getLapsRun()/data.getLapsPerMile())); } <EditText android:id="@+id/mileCount" android:layout_width="100dp" android:layout_height="wrap_content" android:layout_marginTop="110dp" android:inputType="numberDecimal" android:maxLength="4" /> For some reason if I enter a non decimal number such as 3, or 5, it works fine but when I enter a floating point such as 3.4 or 5.8 it force closes. I cant seem to figure out whats going on. Any ideas? Thanks

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  • How to understand other people's CSS architectures?

    - by John
    I am reasonably good with CSS. However, when working with someone else's CSS, it's difficult for me to see the "bigger picture" in their architecture (but i have no problem when working with a CSS sheet I wrote myself). For example, I have no problems using Firebug to isolate and fix cross browser compatibility issues, or fixing a floating issue, or changing the height on a particular element. But if I'm asked to do something drastic such as, "I want the right sidebars of pages A, B, C and D to have a red border. I want the right side bars of pages E, F and G to have a blue border if and only if the user mouses over", then it takes me time a long time to map out all the CSS inheritance rules to see the "bigger picture". For some reason, I don't encounter the same difficulty with backend code. After a quick debriefing of how a feature works, and a quick inspection of the controller and model code, I will feel comfortable with the architecture. I will think, "it's reasonable to assume that there will be an Employee class that inherits from the Person Class that's used by a Department controller". If I discover inconvenient details that aren't consistent with overall architectural style, I am confident that I can hammer things back in place. With someone else's CSS work, it's much harder for me to see the "relationships" between different classes, and when and how the classes are used. When there are many inheritance rules, I feel overwhelmed. I'm having trouble articulating my question and issues... All I want to know is, why is it so much harder for me to see the bigger picture in someone else's CSS architecture than compared to someone else's business logic layer? **Does it have any thing to do with CSS being a relatively new technology, and there aren't many popular design patterns?

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  • Is there a way to receive data as unsigned char over UDP on Qt?

    - by user269037
    I need to send floating point numbers using a UDP connection to a Qt application. Now in Qt the only function available is qint64 readDatagram ( char * data, qint64 maxSize, QHostAddress * address = 0, quint16 * port = 0 ) which accepts data in the form of signed character buffer. I can convert my float into a string and send it but it will obviously not be very efficient converting a 4 byte float into a much longer sized character buffer. I got hold of these 2 functions to convert a 4 byte float into an unsinged 32 bit integer to transfer over network which works fine for a simple C++ UDP program but for Qt I need to receive the data as unsigned char. Is it possible to avoid converting the floatinf point data into a string and then sending it? uint32_t htonf(float f) { uint32_t p; uint32_t sign; if (f < 0) { sign = 1; f = -f; } else { sign = 0; } p = ((((uint32_t)f)&0x7fff)<<16) | (sign<<31); // Whole part and sign. p |= (uint32_t)(((f - (int)f) * 65536.0f))&0xffff; // Fraction. return p; } float ntohf(uint32_t p) { float f = ((p>>16)&0x7fff); // Whole part. f += (p&0xffff) / 65536.0f; // Fraction. if (((p>>31)&0x1) == 0x1) { f = -f; } // Sign bit set. return f; }

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  • Checked and Unchecked operators don't seem to be working when...

    - by flockofcode
    1) Is UNCHECKED operator in effect only when expression inside UNCHECKED context uses an explicit cast ( such as byte b1=unchecked((byte)2000); ) and when conversion to particular type can happen implicitly? I’m assuming this since the following expression throws a compile time error: byte b1=unchecked(2000); //compile time error 2) a) Do CHECKED and UNCHECKED operators work only when resulting value of an expression or conversion is of an integer type? I’m assuming this since in the first example ( where double type is being converted to integer type ) CHECKED operator works as expected: double m = double.MaxValue; b=checked((byte)m); // reports an exception , while in second example ( where double type is being converted to a float type ) CHECKED operator doesn’t seem to be working. since it doesn't throw an exception: double m = double.MaxValue; float f = checked((float)m); // no exception thrown b) Why don’t the two operators also work with expressions where type of a resulting value is of floating-point type? 2) Next quote is from Microsoft’s site: The unchecked keyword is used to control the overflow-checking context for integral-type arithmetic operations and conversions I’m not sure I understand what exactly have expressions and conversions such as unchecked((byte)(100+200)); in common with integrals? Thank you

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  • CSS - Positioning images next to text

    - by jpjoki
    Hi, I'm doing a site in which images need to presented next to textual content - a sort of pseudo two-column layout, as the images and text come from a single html source. I've found quite a simple way to do this by putting the images as their own paragraphs and floating them. Would there still be a more simpler way (in regards to html) to do this without these extra paragraphs and by only attributing extra css to images? If the floated image is in the same paragraph than the text, then paragraphs with and without images would be different in width. EDIT: Basically, I'm looking for as simple HTML markup as possible to position images like this. The CSS can be complex ;) CSS: p { width: 500px; } p.image { float: right; width: 900px; } Current HTML: <p class="image"><img src="image.jpg" /></p> <p>Some text here.</p> Is the above possible with this HTML? <p><img src="image.jpg" /></p>

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  • Long primitive or AtomicLong for a counter?

    - by Rich
    Hi I have a need for a counter of type long with the following requirements/facts: Incrementing the counter should take as little time as possible. The counter will only be written to by one thread. Reading from the counter will be done in another thread. The counter will be incremented regularly (as much as a few thousand times per second), but will only be read once every five seconds. Precise accuracy isn't essential, only a rough idea of the size of the counter is good enough. The counter is never cleared, decremented. Based upon these requirements, how would you choose to implement your counter? As a simple long, as a volatile long or using an AtomicLong? Why? At the moment I have a volatile long but was wondering whether another approach would be better. I am also incrementing my long by doing ++counter as opposed to counter++. Is this really any more efficient (as I have been led to believe elsewhere) because there is no assignment being done? Thanks in advance Rich

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  • using replace to produce javascript code, django

    - by durdenk
    I want to use highcharts with my django site but it requires a comlex javascript code such as below. So I wanted to get this script in my python code and replace apropriate portions then write it in my template, first question is, is this a dump way to do that for a person not knowing javascript. I can read it tough. Second question is, Why I cant replace this string. Lets say this string is a variable like this. lineChartsTemplate = """ ... ... """ if I try and do lineChartsTemplate .replace('dataCategory', dataCategory) it basically suppossed to change dataCategory text with my dataCategory variable, but no such luck. I need guidance here. thx. $(function () { var chart = new Highcharts.Chart({ chart: { renderTo: 'container', type: 'bar' }, xAxis: { categories: dataCategory }, yAxis: { }, legend: { layout: 'vertical', floating: true, backgroundColor: '#FFFFFF', align: 'right', verticalAlign: 'top', y: 60, x: -60 }, tooltip: { formatter: function() { return '<b>'+ this.series.name +'</b><br/>'+ this.x +': '+ this.y; } }, plotOptions: { }, series: [{ data: dataList , name : 'Satislar'}] }); });

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  • Performance when querying a View

    - by Nate Bross
    I'm wondering if this is a bad practice or if in general this is the correct approach. Lets say that I've created a view that combines a few attributes from a few tables. My question, what do I need to do so I can query against this view as if it were a table without worrying about performance? All attributes in the original tables are indexed, my concern is that the result view will have hundreds of thousands of records, which I will want to narrow down quite a bit based on user input. What I'd like to avoid, is having multiple versions of the code that generates this view floating around with a few extra "where" conditions to facilitate the user input filtering. For example, assume my view has this header VIEW(Name, Type, DateEntered) this may have 100,000+ rows (possibly millions). I'd like to be able to make this view in SQL Server, and then in my application write querlies like this: SELECT Name, Type, DateEntered FROM MyView WHERE DateEntered BETWEEN @date1 and @date2; Basically, I am denormalizing my data for a series of reports that need to be run, and I'd like to centralize where I pull the data from, maybe I'm not looking at this problem from the right angle though, so I'm open to alternative ways to attack this.

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  • Centered DIV w/ width dependant on text, buffered by two divs that should fill the containing DIV

    - by Andrew Thompson
    I have been wracking my brains on this seemingly small issue the whole day. My web dev friends are baffled and I could not find a suitable answer in my search of this site and others (though, I could have missed it somewhere along the way). Here's the problem: 3 DIVS within one fixed-width container DIV The center DIV has text that will be different on other sites The center DIV needs to be centered, and no larger than the text it contains. This is what I'd like to end up with The basic HTMl: <div id="container" > <div id="left" ></div> <div id="center" >Text inside center should resize this block</div> <div id="right" ></div> </div> Below, I removed most of the styles I have tried. This CSS currently centers the DIV (if I set it as an inline block), but I need the other divs to fill the left and right space remaining: #container { width:750px; text-align:center; } #left { background-color:#E85355; } #center { background-color:#CDD7D7; display:inline-block; } #right { background-color:#65A8A6; } I've tried floating, no-wrap, overflow, etc. Thanks a million to whomever can offer some help! JSFiddle Link

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  • How can I write a function template for all types with a particular type trait?

    - by TC
    Consider the following example: struct Scanner { template <typename T> T get(); }; template <> string Scanner::get() { return string("string"); } template <> int Scanner::get() { return 10; } int main() { Scanner scanner; string s = scanner.get<string>(); int i = scanner.get<int>(); } The Scanner class is used to extract tokens from some source. The above code works fine, but fails when I try to get other integral types like a char or an unsigned int. The code to read these types is exactly the same as the code to read an int. I could just duplicate the code for all other integral types I'd like to read, but I'd rather define one function template for all integral types. I've tried the following: struct Scanner { template <typename T> typename enable_if<boost::is_integral<T>, T>::type get(); }; Which works like a charm, but I am unsure how to get Scanner::get<string>() to function again. So, how can I write code so that I can do scanner.get<string>() and scanner.get<any integral type>() and have a single definition to read all integral types? Update: bonus question: What if I want to accept more than one range of classes based on some traits? For example: how should I approach this problem if I want to have three get functions that accept (i) integral types (ii) floating point types (iii) strings, respectively.

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  • Timing issues with playback of the HTML5 Audio API

    - by pat
    I'm using the following code to try to play a sound clip with the HTML5 Audio API: HTMLAudioElement.prototype.playClip = function(startTime, stopTime) { this.stopTime = stopTime; this.currentTime = startTime; this.play(); $(this).bind('timeupdate', function(){ if (this.ended || this.currentTime >= stopTime) { this.pause(); $(this).unbind('timeupdate'); } }); } I utilize this new playClip method as follows. First I have a link with some data attributes: <a href=# data-stop=1.051 data-start=0.000>And then I was thinking,</a> And finally this bit of jQuery which runs on $(document).ready to hook up a click on the link with the playback: $('a').click(function(ev){ $('a').click(function(ev){ var start = $(this).data('start'), stop = $(this).data('stop'), audio = $('audio').get(0), $audio = $(audio); ev.preventDefault(); audio.playClip(start,stop); }) This approach seems to work, but there's a frustrating bug: sometimes, the playback of a given clip plays beyond the correct data-stop time. I suspect it could have something to do with the timing of the timeupdate event, but I'm no JS guru and I don't know how to begin debugging the problem. Here are a few clues I've gathered: The same behavior appears to come up in both FF and Chrome. The playback of a given clip actually seems to vary a bit -- if I play the same clip a couple times in a row, it may over-play a different amount of time on each playing. Is the problem here the inherent accuracy of the Audio API? My app needs milliseconds. Is there a problem with the way I'm using jQuery to bind and unbind the timeupdate event? I tried using the jQuery-less approach with addEventListener but I couldn't get it to work. Thanks in advance, I would really love to know what's going wrong.

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  • Detecting the axis of rotation from a pointcloud

    - by tfinniga
    I'm trying to auto-detect the axis of rotation on a 3d pointcloud. In other words, if I took a small 3d pointcloud, chose a single axis of rotation, and make several copies of the points at different rotation angles, then I get a larger pointcloud. The input to my algorithm is the larger pointcloud, and the desired output is the single axis of symmetry. And eventually I'm going to compute the correspondences between points that are rotations of each other. The size of the larger pointcloud is on the order of 100K points, and the number of rotational copies made is unknown. The rotation angles in my case have constant deltas, but don't necessarily span 360 degrees. For example, I might have 0, 20, 40, 60. Or I might have 0, 90, 180, 270. But I won't have 0, 13, 78, 212 (or if I do, I don't care to detect it). This seems like a computer vision problem, but I'm having trouble figuring out how to precisely find the axis. The input will generally be very clean, close to float accuracy.

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  • SVG text - total length changes depending on zoom

    - by skco
    In SVG (for web-browsers), if i add a <text>-element and add some text to it the total rendered width of the text string will change depending on the scale of the text. Lets say i add "mmmmmmmmmmmmmmmmmmmmmmmmmmA" as text, then i want to draw a vertical line(or other exactly positioned element) intersecting the very last character. Works fine but if i zoom out the text will become shorter or longer and the line will not intersect the text in the right place anymore. The error can be as much as +/- 5 characters width which is unacceptable. The error is also unpredictable, 150% and 160% zoom can add 3 characters length while 155% is 2 charlengths shorter. My zoom is implemented as a scale-transform on the root element of my canvas which is a <g>. I have tried to multiply the font-size with 1000x and scale down equally on the zoom-transform and vice versa in case it was a floating point error but the result is the same. I found the textLength-attribute[1] which is supposed to adjust the total length so the text always end where i choose but it only works in Webkit. Firefox and Opera seems to not care at all about this value (haven't tried in IE9 yet). Is there any way to render text exactly positioned without resorting to homemade filling of font-outlines? [1] http://www.w3.org/TR/SVG11/text.html#TextElementTextLengthAttribute Update Snippet of the structure i'm using <svg> <g transform="scale(1)"> <!--This is the root, i'm changing the scale of this element to zoom --> <g transform="scale(0.014)"> <!--This is a wrapper for multi-line text, scaling, other grouping etc --> <text font-size="1000" textLength="40000">ABDCDEFGHIJKLMNOPQRSTUVXYZÅÄÖabcdefghijklmnopqrstxyzåäö1234567890</text> </g> </g>

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  • Zend Framework: How do I modify/format the form view generated with Zend_Dojo_Form elements

    - by pinardelrio
    I have created a form: <?php class Application_Form_Issue extends Zend_Dojo_Form { public function init() { $this->setName('issue'); $this->setMethod('post'); $id = new Zend_Form_Element_Hidden('id'); $id->addFilter('Int'); $date_recvd = new Zend_Dojo_Form_Element_DateTextBox('date_recvd'); $date_recvd->setLabel('Date Received') //->setRequired(true) /*->addValidator('NotEmpty'); */; More Form elements ... To view this form my view script is: <?php echo $this->form; ?> This all works just fine, with fully functional dojo form elements (datepicker, timepicker, etc) and successfully saving the data. However, now, I want to format the form that is generated with css. Such as grouping some elements and floating left or right, making some input text fields wider/narrower, etc. How? I realize I can modify the view script but it seems like that defeats the purpose of using Zend_Dojo_Form or Zend_Form. Is that a correct assumption?

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  • can I store an id value in array of float type ?

    - by srikanth rongali
    I used, for(id value in values) to get the value from an NSArray. Now I want to store it in 2 dimensional float array[][]. When I try to assign the values to array it is giving error:incompatible types in assignment. I tried to cast the value but I got error: pointer value used where a floating point value was expected. I need to store the values in an 2 dimensional array . How can I make it ? Thank You. @implementation fromFileRead1 NSString *fileNameString; int numberOfEnemies, numberOfValues; -(id)init { if( (self = [super init]) ) { NSString *path = @"/Users/sridhar/Desktop/Projects/exampleOnFile2/enemyDetals.txt"; NSString *contentsOfFile = [[NSString alloc] initWithContentsOfFile:path]; NSArray *lines = [contentsOfFile componentsSeparatedByString:@"\n"]; numberOfEnemies = [lines count]; NSLog(@"The number of Lines: %d", numberOfEnemies); for (id line in lines) { NSLog(@"Line %@", line ); NSString *string1 = line; NSArray *split1 = [string1 componentsSeparatedByString:@","]; numberOfValues = [split1 count]; NSLog(@"The number of values in Row: %d", numberOfValues); for (id value in split1) { NSLog(@"value %@", value); float value1; value1 = [split1 objectAtIndex:2]); NSLog(@"VAlue of Value1 at index 2: %f", value1 ); } } } return self; } @end In enemyDetal.txt I have 1,3,3 2,3,2.8 10,2,1.6

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  • How to detect iPhone movement in space using accelerometer ?

    - by super_tomtom
    Hi ! I am trying to make an application that would detect what kind of shape you made with your iPhone using accelerometer. As an example, if you draw a circle with your hand holding the iPhone, the app would be able to redraw it on the screen. This could also work with squares, or even more complicated shapes. The only example of application I've seen doing such a thing is AirPaint (http://vimeo.com/2276713), but it doesn't seems to be able to do it in real time. My first try is to apply a low-pass filter on the X and Y parameters from the accelerometer, and to make a pointer move toward these values, proportionally to the size of the screen. But this is clearly not enought, I have a very low accuracy, and if I shake the device it also makes the pointer move... Any ideas about that ? Do you think accelerometer data is enought to do it ? Or should I consider using other data, such as the compass ? Thanks in advance !

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  • Web UI element to represent two different micro-views of data in the same spot?

    - by Chris McCall
    I've been tasked with laying out a portion of a screen for a customer care (call center) app that serves as sort of a header/summary block at the top of the screen. Here's what it looks like: The important part is in the red box. That little tooltip is the biz's vision for how to represent both the numeric SiteId and the textual Site Name all in the same piece of screen real estate. I asked, and the business thinks the Name is more important than the ID, but lists the Id by default, because the Name can't be truncated in the display, and there's only so much horizontal room to put the data. So they go with the Id, because it's fewer characters, and then they have the user mouse-over the Id to display the name (presumably because the tooltip can be of unlimited width and since it's floating over the rest of the screen, the full name will always be displayed. So, here's my question: Is there some better UI metaphor that I don't know about that could get this job done, while meeting the following constraints?: Does not require the mouse (uses a keyboard shortcut to do the "reveal") Allows the user to copy and paste the name Will not truncate the name Provides for the display of both the ID and name in the same spot Works with IE7

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  • style ul with width to accommodate items

    - by Tallmaris
    Sorry I could not find a similar answer on SO. I have the following markup (generated by jquery ui autocomplete but this is not the issue here) <ul style="z-index: 1; display: block; border: thin solid red; width: 200px;"> <li> <a> <div style="font-size: 0.85em;"> <span style="float: right; padding-left: 10px; color: gray;"> United Kingdom </span> <span style="">text text text text text</span> </div> </a> </li> </ul> As you can see in this fiddle: http://jsfiddle.net/fVr8P/2/ the text wraps because the width is limited and the country span is "floating". What I would like would be for the width to enlarge to accommodate the full length, but if I put width: auto; it will expand to 100%. Background The ul is of course coming from jquery ui autocomplete. I am styling the results a bit using the autocomplete.html extension. Problem is that everything is working ok in firefox an chrome because the autocomplete is set to the correct width on creation. in IE this does not happen (width is too small) so the text wraps. I am hping to come to a simple css only solution, without fiddling around in jQuery.

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  • Embedded Development Board

    - by ALF3130
    I'm new to the embedded development world and am looking to get my very first board. After some research, I realize that there aren't many choices with FPUs. This is important in my project as I'm going to be doing quite a bit of floating point computations. I found the Mini2440 which seems to run on the ARM920T core. This particular unit is perfect for my needs (decent price, all the right I/O ports, and a touch screen to boot) but it seems that it doesn't have an FPU. I don't know how big of a penalty I'd be paying for FP emulation, so I'm unsure of whether to pull the trigger on this one. That said: Can someone please confirm whether this product (Mini2440) has an FPU or not? My project will do image capture and analysis. Does anyone have any experience with running things like OpenMP on such platforms? Please suggest any other similar boards in the = $200 price range that have an FPU. This world is new to me. Any other advice or things I should be aware of is much appreciated.

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  • Preserving the order of annotations

    - by Ragunath Jawahar
    When obtaining the list of fields using getFields() and getDeclaredFields(), the order of the fields in a Java class is undefined. I need this order in my validation library. Since the order is not preserved (though some claim that the order is preserved in JDK 6 and above but is not guaranteed across VMs). I cannot speculate on this because the order of annotations across fields is absolutely essential for the library. One way to get around this is to have an order or an index attribute in my Annotation. What worries me is that the code could become a bit cumbersome for maintaining in the following case. If the use wants to insert a new annotated field then, he might have to renumber all the other annotations in the class. I could have the order or index as a floating point number - float or double but , it wouldn't look good to have order such as 1, 1.5, 2, etc., What would be an elegant solution for this problem? Here is a example code so that you can get an idea about the problem: @Required @TextRule (minLength = 6, message = "You need at least 6 characters.") private EditText usernameEditText; @Password private EditText passwordEditText; @ConfirmPassword private EditText confirmPasswordEditText; @Email private EditText emailEditText;

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  • Calculations on the iteration count in for loop in Ruby 1.8.7

    - by user1805035
    I was playing around with Ruby and Latex to create a color coding set. I'm more than a novice with C++, but haven't looked at Ruby until now. So, still learning a lot of coding. I have the following block of code below. When attempting to run this, band1 = 1e+02. I've tried band1 = (BigDecimal(i) * 100).to_f thinking maybe there was some odd floating point issue. This is just me trying anything though as an integer multiplied by an integer should create an integer, if I'm still thinking correctly. I've tried a variety of other things as well (things that I can do in C++, but this ain't C++), but to no avail. (1..9).each do |i| #Band 1 (0..9).each do |j| #Band 2 (0..11).each do |k| #Band 3 #Band 3 Start #these are the colors of the resistor bands b1 = $c_band12[i] b2 = $c_band12[j] b3 = $c_band3[k] b4 = "Gold" oms = ((i*100) + (j*10)) * $mult[k] band1 = i*100 band2 = j band3 = $mult[k] end end end Not sure what I'm missing. Should I be using .each_with_index through these iterations? I've tried this: (1..9).each_with_index {|i, indexi| #Band 1 (0..9).each_with_index {|j, indexj| #Band 2 (0..11).each_with_index {|k, indexk| #Band 3 #Band 3 Start #these are the colors of the resistor bands b1 = $c_band12[i] b2 = $c_band12[j] b3 = $c_band3[k] b4 = "Gold" oms = ((i*100) + (j*10)) * $mult[k] band1 = indexk * 100 and I get the same answer. I can't see why 1*100 should equate to such a large number? Thank you, AT

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  • Calculating with a variable outside of its bounds in C

    - by aquanar
    If I make a calculation with a variable where an intermediate part of the calculation goes higher then the bounds of that variable type, is there any hazard that some platforms may not like? This is an example of what I'm asking: int a, b; a=30000; b=(a*32000)/32767; I have compiled this, and it does give the correct answer of 29297 (well, within truncating error, anyway). But the part that worries me is that 30,000*32,000 = 960,000,000, which is a 30-bit number, and thus cannot be stored in a 16-bit int. The end result is well within the bounds of an int, but I was expecting that whatever working part of memory would have the same size allocated as the largest source variables did, so an overflow error would occur. This is just a small example to show my problem, I am trying to avoid using floating points by making the fraction be a fraction of the max amount able to be stored in that variable (in this case, a signed integer, so 32767 on the positive side), because the embedded system I'm using I believe does not have an FPU. So how do most processors handle calculations out of the bounds of the source and destination variables?

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  • SQL SERVER – Update Statistics are Sampled By Default

    - by pinaldave
    After reading my earlier post SQL SERVER – Create Primary Key with Specific Name when Creating Table on Statistics, I have received another question by a blog reader. The question is as follows: Question: Are the statistics sampled by default? Answer: Yes. The sampling rate can be specified by the user and it can be anywhere between a very low value to 100%. Let us do a small experiment to verify if the auto update on statistics is left on. Also, let’s examine a very large table that is created and statistics by default- whether the statistics are sampled or not. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Million Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 1000000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO Now let us observe the result of the DBCC SHOW_STATISTICS. The result shows that Resultset is for sure sampling for a large dataset. The percentage of sampling is based on data distribution as well as the kind of data in the table. Before dropping the table, let us check first the size of the table. The size of the table is 35 MB. Now, let us run the above code with lesser number of the rows. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Hundred Thousand Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 100000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO You can see that Rows Sampled is just the same as Rows of the table. In this case, the sample rate is 100%. Before dropping the table, let us also check the size of the table. The size of the table is less than 4 MB. Let us compare the Result set just for a valid reference. Test 1: Total Rows: 1000000, Rows Sampled: 255420, Size of the Table: 35.516 MB Test 2: Total Rows: 100000, Rows Sampled: 100000, Size of the Table: 3.555 MB The reason behind the sample in the Test1 is that the data space is larger than 8 MB, and therefore it uses more than 1024 data pages. If the data space is smaller than 8 MB and uses less than 1024 data pages, then the sampling does not happen. Sampling aids in reducing excessive data scan; however, sometimes it reduces the accuracy of the data as well. Please note that this is just a sample test and there is no way it can be claimed as a benchmark test. The result can be dissimilar on different machines. There are lots of other information can be included when talking about this subject. I will write detail post covering all the subject very soon. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics

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