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• Mathematica Plot3D does not produce a plot when graphing a user-defined function?

  - by pythonscript

  I'm writing a simple Mathematica implementation of the black-scholes model and using Plot3D to plot the pricing surface. However, when I run this code, no plot is produced. My call and put functions to produce correct values when run separately, but no plot is produced. Code: Clear[d1, d2, call, put, stockPrice, strikePrice, riskFreeRate, timeToExp, volatility] d1[stockPrice_, strikePrice_, riskFreeRate_, timeToExp_, volatility_] := (Log[stockPrice / strikePrice] + (riskFreeRate + 0.5*volatility^2)*timeToExp) / (volatility * Sqrt[timeToExp]) d2[stockPrice_, strikePrice_, riskFreeRate_, timeToExp_, volatility_] := d1[stockPrice, strikePrice, riskFreeRate, timeToExp, volatility] - volatility*Sqrt[timeToExp] call[stockPrice_, strikePrice_, riskFreeRate_, timeToExp_, volatility_] := stockPrice * CDF[NormalDistribution[0, 1], d1[stockPrice, strikePrice, riskFreeRate, timeToExp, volatility]] - strikePrice * Exp[-riskFreeRate*timeToExp] *CDF[NormalDistribution[0, 1], d2[stockPrice, strikePrice, riskFreeRate, timeToExp, volatility]] Plot3D[call[stockPrice, 500, 0.0030, timeToExp, 0.39], {stockPrice, 10, 1000}, {timetoExp, 0.0833333, 5}] Other plots, like this sample from the reference, do work. Plot3D[{x^2 + y^2, -x^2 - y^2}, {x, -2, 2}, {y, -2, 2}, RegionFunction -> Function[{x, y, z}, x^2 + y^2 <= 4], BoxRatios -> Automatic]

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• Customized User Registration Form

  - by Nitz

  Hey Guys, i have made user-register.tpl.php file. And i have set many text field in that. But now i need that.... i want to store the users information to the database. bcz i have created the customized registration page, so i need that my text field values should be store in the database. like this....... Username: <input type="text" name="myuser" id="myuser" /> Now i want to store the username, which will entered in this myuser text filed. NitishPanchjanya Corporation

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• How apply Unit tests in ASP.NET webforms

  - by gre3ns0ul

  Hi guys. I'm developing a website in asp.net webforms with 3 layers; UI, BLL and DAL The website is already developed, but i like have more control about the unit tests of each form Pass specific values at specific inputs for i see, if application survives or not. I already study about NUnit but in webforms in UI layer how can apply these tests? What i wnat is get some way to test UI (validations) without have to access to the BLL as i was an user. I'm trying to add the Unit tests to my app but i not sure how to do it! somebody can help my small-bigger problem? apreciated

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• C language preprocessor behavior

  - by khanna_param

  There are different kind of macros in C language, nested macro is one of them. Considering a program with the following macro #define HYPE(x,y) (SQUR(x)+SQUR(y)) #define SQUR(x) (x*x) Using this we can successfully compile to get the result. As we all know the C preprocessor replaces all the occurrence of the identifiers with the replacement-string. Considering the above example I would like to know how many times the C preprocessor traverses the program to replace the macro with the replacement values. I assume it cannot be done in one go.

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• Calculate cubic bezier T value where tangent is perpendicular to anchor line.

  - by drawnonward

  Project a cubic bezier p1,p2,p3,p4 onto the line p1,p4. When p2 or p3 does not project onto the line segment between p1 and p4, the curve will bulge out from the anchor points. Is there a way to calculate the T value where the tangent of the curve is perpendicular to the anchor line? This could also be stated as finding the T values where the projected curve is farthest from the center of the line segment p1,p4. When p2 and p3 project onto the line segment, then the solutions are 0 and 1 respectively. Is there an equation for solving the more interesting case? The T value seems to depend only on the distance of the mapped control points from the anchor line segment. I can determine the value by refining guesses, but I am hoping there is a better way.

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• Model Binding using ASP.NET MVC, getting datainput to the controller.

  - by Calibre2010

  Pretty Basic one here guys. I have a View which holds 2 textfields for input and a submit button <%using (Html.BeginForm("DateRetrival", "Home", FormMethod.Post)){ %> <%=Html.TextBox("sday")%> <%=Html.TextBox("eday")%> <input type="submit" value="ok" id="run"/> <% }%> the following controller action which I want to bind the data input is as follows [AcceptVerbs(HttpVerbs.Get)] public ActionResult DateRetrival() { return View(); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult DateRetrival(string submit) { return null; } When I debug this and look in the action methods parameter, the value is null. When I've entered values in both textboxes and and clicked the submit method.

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• How does Bitmap.Save(Stream, ImageFormat) format the data?

  - by Matt Jacobsen

  I have a non transparent, colour bitmap with length 2480 and width 3507. Using Bitmap.GetPixel(int x, int y) I am able to get the colour information of each pixel in the bitmap. If I squirt the bitmap into a byte[]: MemoryStream ms = new MemoryStream(); bmp.Save(ms, ImageFormat.Bmp); ms.Position = 0; byte[] bytes = ms.ToArray(); then I'd expect to have the same information, i.e. I can go to bytes[1000] and read the colour information for that pixel. It turns out that my array of bytes is larger than I anticipated. I thought I'd get an array with 2480 x 3507 = 8697360 elements. Instead I get an array with 8698438 elements - some sort of header I presume. In what format the bytes in my array stored? Is there a header 1078 bytes long followed by Alpha, Red, Green, Blue values for every byte element, or something else?

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• Reset UITextField's original placeholder text

  - by Michael

  I'm adding some user feedback mechanism into my app. The user types some comments into a text field and when that editing is done it updates a UITextView. Then when the user hits the submit button and moves on in the app the user may have need to send more feedback from the same form for a different item. I can reset the other fields and labels in the app to their default values when I hide the view, but not the textField (?). How can I reestablish the placeholder text next time the user accesses this view? Your suggestions are humbly appreciated.

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• On Edit Grid view Multiple row edit validation

  - by franics

  I am using a telerik radgrid so there are around 5 columns each column edittemplate contains a control along with a required field validator and also a property called AllowMultiRowEdit is set to true so i am able to multiple rows in edit mode. If any of the values are cleared the for multiple rows I want only those to be validated on update of that particular row. So i implemented the Grids item data bound event find each and every validator along with the update button and set a unique validation group. The above implementation most times but fails at some time. Is there any other way of going about this ?

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• In Applescript, why do local variables in handlers capture "with" labeled parameters?

  - by outis

  In Applescript, if you declare a handler using "with" labeled parameters, local variables get the values of the arguments and the parameters themselves are undefined. For example: on bam of thing with frst and scnd local eat_frst return {thing: thing, frst:frst, scnd:scnd} -- this line throws an error end bam bam of "bug-AWWK!" with frst without scnd results in an error message that "scnd" isn't defined in the second line of bam. thing and frst are both defined, getting the arguments passed in the call to bam. Why is this happening? Why is scnd undefined? Note: I know that declaring variables as "local" within a handler is unnecessary. It's done in the examples for illustrative purposes.

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• problem in return value from server to client in ajax useing zend-framework

  - by user1400

  hello i try to use ajax and zend in my application , i could pass variable to server but i can not get data from server , it does not return values, it return all html code page, where is my mistake? $('#myForm').submit(function($e){ $e.preventDefault(); var $paramToServer=$("#myForm").serialize(); $.ajax({ type:'POST', url:'test', data:$paramToServer , success:function(re){ var res = $.evalJSON(re); console.log(res.id); // to see in firebog }, dataType:'json' }); }); public function testAction() { // action body $this->_helper->getHelper('viewRenderer')->setNoRender(); // If you use layout, disable it Zend_Layout::getMvcInstance()->disableLayout(); $name=$this->getRequest()->getParam ( 'name' ); //pass $name to server $return = array( 'id' => '5', 'family' => 'hello ', ); $return = Zend_Json::encode( $return); // Response $this->getResponse()->setBody($return); }

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• DataBinding and ErrorProvider - How to provide custom error messages?

  - by BeowulfOF

  We use BusinessObjects, implementing IDataErrorInfo and IEditableObject. BindingLists with those Objects are added to BindingSources, those are used to bind UserControls and DataGrids on the forms (WinForms). The BindingSource is additionally set as DataSource to the ErrorProvider of the form. We do use currently TextBoxes for Properties of Type int and short. They are validated inside the BusinessObjects with custom validation, like min/max values, etc. That works fine, since error message form our custom validations show up nicely next to the TextBox. However, if the input is greater than the value of an int (e.g. "9999999999") the BindingSource doesn't even try to enter that Value into the BusinesObject but instead gives the errormessage to the errorprovider like "The value for Int32 was too big.". We do not want to bother our users with "Int32" but want a custom errormessage for that. It is nice, that the BindingSource does provide this feature, but is it possible to provide custom error messages for this?

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• C# LINQ Where Predicate Type Arguments

  - by blu

  I have an XElement with values for mock data. I have an expression to query the xml: Expression<Func<XElement, bool>> simpleXmlFunction = b => int.Parse(b.Element("FooId").Value) == 12; used in: var simpleXml = xml.Elements("Foo").Where(simpleXmlFunction).First(); The design time error is: The type arguments for method 'System.Linq.Enumerable.Where(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly' The delegate supplied to Where should take in an XElement and return a bool, marking if the item matches the query, I am not sure how to add anything more to the delegate or the where clause to mark the type. Also, the parallel method for the real function against the Entity Framework does not have this issue. What is not correct with the LINQ-to-XML version?

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• Depth First Search Basics

  - by cam

  I'm trying to improve my current algorithm for the 8 Queens problem, and this is the first time I'm really dealing with algorithm design/algorithms. I want to implement a depth-first search combined with a permutation of the different Y values described here: http://en.wikipedia.org/wiki/Eight_queens_puzzle#The_eight_queens_puzzle_as_an_exercise_in_algorithm_design I've implemented the permutation part to solve the problem, but I'm having a little trouble wrapping my mind around the depth-first search. It is described as a way of traversing a tree/graph, but does it generate the tree graph? It seems the only way that this method would be more efficient only if the depth-first search generates the tree structure to be traversed, by implementing some logic to only generate certain parts of the tree. So essentially, I would have to create an algorithm that generated a pruned tree of lexigraphic permutations. I know how to implement the pruning logic, but I'm just not sure how to tie it in with the permutation generator since I've been using next_permutation. Is there any resources that could help me with the basics of depth first searches or creating lexigraphic permutations in tree form?

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• Best way of implementing DropDownList in ASP.NET MVC 2?

  - by Kelsey

  I am trying to understand the best way of implementing a DropDownList in ASP.NET MVC 2 using the DropDownListFor helper. This is a multi-part question. First, what is the best way to pass the list data to the view? Pass the list in your model with a SelectList property that contains the data Pass the list in via ViewData How do I get a blank value in the DropDownList? Should I build it into the SelectList when I am creating it or is there some other means to tell the helper to auto create an empty value? Lastly, if for some reason there is a server side error and I need to redisplay the screen with the DropDownList, do I need to fetch the list values again to pass into the view model? This data is not maintained between posts (at least not when I pass it via my view model) so I was going to just fetch it again (it's cached). Am I going about this correctly?

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• geom_tile heatmap with different high fill colours based on factor

  - by Michael

  I'm interested in building a heatmap with geom_tile in ggplot2 that uses a different gradient high color based on a factor. The plot below creates the plot where the individual tiles are colored blue or red based on the xy_type, but there is no gradient. ggplot() + geom_tile(data=mydata, aes(x=factor(myx), y=myy, fill=factor(xy_type))) + scale_fill_manual(values=c("blue", "red")) The plot below does not use the xy_type factor to choose the color, but I get a single group gradient based on the xy_avg_value. ggplot() + geom_tile(data=mydata, aes(x=factor(myx), y=myy, fill=xy_avg_value)) Is there a technique to blend these two plots? I can use a facet_grid(xy_type ~ .) to create separate plots of this data, with the gradient. As this is ultimately going to be a map (x~y coordinates), I'd like to find a way to display the different gradient together in a single geom_tile map.

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• Implementing password hashing/salting algorithm from crackstation.net

  - by Mason240

  I am trying to implement a password hashing/salting algorithm from crackstation.net, but I am unsure how implement it. Storing the password upon user registration seems to be as simple as passing the password into create_hash(). $password = create_hash($_POST['Password']; I'm not following how to validate upon user login. validate_password($password, $good_hash) returns either true or false, and takes $password as parameter, so it seems like a no brainer except for the second parameter $good_hash. Where does this param come from? It is my understanding that password is turned into a hash value every time its used, and that the hash value is what is stored and compared. So why would I have both the $password and $good_hash values? Quick overview of the functions: function create_hash($password){ calls pbkdf2() } function validate_password($password, $good_hash){ calls pbkdf2() calls slow_equals() } function slow_equals($a, $b){ } function pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false){ } Of course a different, better method for this would also be just as helpful. Thank you

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• Import a Collada model doesn't align to pixels

  - by Dan Friedman

  Assume I have a model that is simply a cube. (It is more complicated than a cube, but for the purposes of this discussion, we will simplify.) So when I am in Sketchup, the cube is Xmm by Xmm by Xmm, where X is an integer. I then export the a Collada file and subsequently load that into threejs. Now if I look at the geometry bounding box, the values are floats, not integers. So now assume I am putting cubes next to each other with a small space in between say 1 pixel. Because screens can't draw half pixels, sometimes I see one pixel and sometimes I see two, which causes a lack of uniformity. I think I can resolve this satisfactorily if I can somehow get the imported model to have integer dimensions. I have full access to all parts of the model starting with Sketchup, so any point in the process is fair game. Is it possible? Thanks.

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• Update multiple rows with one query?

  - by kavoir.com

  I found something that works with updating one field at here: http://www.karlrixon.co.uk/articles/sql/update-multiple-rows-with-different-values-and-a-single-sql-query/ UPDATE person SET name = CASE id WHEN 1 THEN 'Jim' WHEN 2 THEN 'Mike' WHEN 3 THEN 'Precious' END WHERE id IN (1,2,3) My question is how to update more than one field? Such as: UPDATE person SET name = CASE, sex = CASE id WHEN 1 THEN 'Jim', 'female' WHEN 2 THEN 'Mike' 'male' WHEN 3 THEN 'Precious', 'male' END WHERE id IN (1,2,3) Which doesn't work of course. Tried a few other combination and failed. Any idea? Thanks!

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• Adding ivars to NSManagedObject subclass

  - by The Crazy Chimp

  When I create an entity using core data then generate a subclass of NSManagedObject from it I get the following output (in the .h): @class Foo; @interface Foo : NSManagedObject @property (nonatomic, retain) NSString *name; @property (nonatomic, retain) NSSet *otherValues; @end However, in my .m file I want to make use of the name and otherValues values. Normally I would simply create a couple of ivars and then add the properties for them as I required. That way I can access them in my .m file easily. In this situation would it be acceptable to do this? Would adding ivars to the .h (for name and otherValues) cause any unusual behaviour in the persistance & retrieval of objects?

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• Unchecked call to compareTo

  - by Dave Jarvis

  Background Create a Map that can be sorted by value. Problem The code executes as expected, but does not compile cleanly: http://pastebin.com/bWhbHQmT The syntax for passing Comparable as a generic parameter along to the Map.Entry<K, V> (where V must be Comparable?) -- so that the (Comparable) typecast shown in the warning can be dropped -- eludes me. Warning Compiler's cantankerous complaint: SortableValueMap.java:24: warning: [unchecked] unchecked call to compareTo(T) as a member of the raw type java.lang.Comparable return ((Comparable)entry1.getValue()).compareTo( entry2.getValue() ); Question How can the code be changed to compile without any warnings (without suppressing them while compiling with -Xlint:unchecked)? Related TreeMap sort by value How to sort a Map on the values in Java? http://paaloliver.wordpress.com/2006/01/24/sorting-maps-in-java/ Thank you!

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• transform longitude latitude into meters

  - by Sponge

  I need a function that maps gps positions to x/y values like this: getXYpos(GeoPoint relativeNullPoint, GeoPoint p){ deltaLatitude=p.latitude-relativeNullPoint.latitude; deltaLongitude=p.longitude-relativeNullPoint.longitude; ... resultX=latitude (or west to east) distance in meters from p to relativeNullPoint resultY=longitude (or south to north) distance in meters from p to relativeNullPoint } i have seen some implementations of "distance of two geoPoints" but they all just calculate the air-line distance. i think the deltaLongitude can be transformed into meters directly but the deltaLatitude depends in the Longitude. does anyone know how this problem can be solved?

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• Using a check contraint in MySQL for controlling string length

  - by ptrn

  I'm tumbled with a problem! I've set up my first check constraint using MySQL, but unfortunately I'm having a problem. When inserting a row that should fail the test, the row is inserted anyway. The structure: CREATE TABLE user ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, uname VARCHAR(10) NOT NULL, fname VARCHAR(50) NOT NULL, lname VARCHAR(50) NOT NULL, mail VARCHAR(50) NOT NULL, PRIMARY KEY (id), CHECK (LENGTH(fname) > 30) ); The insert statement: INSERT INTO user VALUES (null, 'user', 'Fname', 'Lname', '[email protected]'); The length of the string in the fname column should be too short, but it's inserted anyway. I'm pretty sure I'm missing something basic here.

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• Oracle: '= ANY()' vs. 'IN ()'

  - by eidylon

  Hi all, I just stumbled upon something in ORACLE SQL (not sure if it's in others), that I am curious about. I am asking here as a wiki, since it's hard to try to search symbols in google... I just found that when checking a value against a set of values you can do WHERE x = ANY (a, b, c) As opposed to the usual WHERE x IN (a, b, c) So I'm curious, what is the reasoning for these two syntaxes? Is one standard and one some oddball Oracle syntax? Or are they both standard? And is there a preference of one over the other for performance reasons, or ? Just curious what anyone can tell me about that '= ANY' syntax. CheerZ!

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• JQuery Access Elements in Modified DOM

  - by Bernhard

  Hi there, im trying since a long term to use events on elements in my dom which has been added asynchronus. I´ve read something about bind but is there a different Way to etablish something like this? For Example I have this situation. $.getJQUERY(myUrl, {var:value}, function(i, data){ $.each(data.values, function(value){ $("body").append('<div id="div_no_'+i+'">'+value+'</div>); // Here i dont want to place the EventListeners }) }); $("div_no_1").click(function(){ // do something }); Could someone help me to find a way to etablish something like this?? Thank you in advance Great Bernhard

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