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  • What is the difference between using MD5.Create and MD5CryptoServiceProvider?

    - by byte
    In the .NET framework there are a couple of ways to calculate an MD5 hash it seems, however there is something I don't understand; What is the distinction between the following? What sets them apart from eachother? They seem to product identical results: public static string GetMD5Hash(string str) { MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider(); byte[] bytes = ASCIIEncoding.Default.GetBytes(str); byte[] encoded = md5.ComputeHash(bytes); StringBuilder sb = new StringBuilder(); for (int i = 0; i < encoded.Length; i++) sb.Append(encoded[i].ToString("x2")); return sb.ToString(); } public static string GetMD5Hash2(string str) { System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create(); byte[] bytes = Encoding.Default.GetBytes(str); byte[] encoded = md5.ComputeHash(bytes); StringBuilder sb = new StringBuilder(); for (int i = 0; i < encoded.Length; i++) sb.Append(encoded[i].ToString("x2")); return sb.ToString(); }

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  • add width li's to parent ul

    - by Epco
    i would like to calculate the width of the li's for each submenu en then put in the ul element. example <ul> <li>level 1</li> <li> <ul style="widht:??;"> // total width li's added here 70px <li>level 2</li> // width of this li 20px <li>level 2</li>/ width of this li 50px </ul> </li> <li>level 1</li> <li>level 1 <ul style="widht:??;"> // total width li's added here 70px <li>level 2</li> // width of this li 20px <li>level 2</li>/ width of this li 50px </ul> </li> </ul> i have this so fare if ('#menu li:has(ul) ul'){ $('li').each(function(){ widthParentUl += $(this).outerWidth(true) }); $(this)parent.('ul').attr('style','width:' + widthParentUl +'px; display:block; background:red;'); }

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  • correcting fisheye distortion programmatically

    - by Will
    I have some points that describe positions in a picture taken with a fisheye lens. I've found this description of how to generate a fisheye effect, but not how to reverse it. How do you calculate the radial distance from the centre to go from fisheye to rectilinear? My function stub looks like this: Point correct_fisheye(const Point& p,const Size& img) { // to polar const Point centre = {img.width/2,img.height/2}; const Point rel = {p.x-centre.x,p.y-centre.y}; const double theta = atan2(rel.y,rel.x); double R = sqrt((rel.x*rel.x)+(rel.y*rel.y)); // fisheye undistortion in here please //... change R ... // back to rectangular const Point ret = Point(centre.x+R*cos(theta),centre.y+R*sin(theta)); fprintf(stderr,"(%d,%d) in (%d,%d) = %f,%f = (%d,%d)\n",p.x,p.y,img.width,img.height,theta,R,ret.x,ret.y); return ret; } Alternatively, I could somehow convert the image from fisheye to rectilinear before finding the points, but I'm completely befuddled by the OpenCV documentation. Is there a straightforward way to do it in OpenCV, and does it perform well enough to do it to a live video feed?

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  • Capturing time intervals when somebody was online? How would you impement this feature?

    - by Kirzilla
    Hello, Our aim is to build timelines saying about periods of time when user was online. (It really doesn't matter what user we are talking about and where he was online) To get information about onliners we can call API method, someservice.com/api/?call=whoIsOnline whoIsOnline method will give us a list of users currently online. But there is no API method to get information about who IS NOT online. So, we should build our timelines using information we got from whoIsOnline. Of course there will be a measurement error (we can't track information in realtime). Let's suppose that we will call whoIsOnline method every 2 minutes (yes, we will run our script by cron every 2 minutes). For example, calling whoIsOnline at 08:00 will return Peter_id Michal_id Andy_id calling whoIsOnline at 08:02 will return Michael_id Andy_id George_id As you can see, Peter has gone offline, but we have new onliner - George. Available instruments are Db(MySQL) / text files / key-value storage (Redis/memcache); feel free to choose any of them (or even all of them). So, we have to get information like this George_id was online... 12 May: 08:02-08:30, 12:40-12:46, 20:14-22:36 11 May: 09:10-12:30, 21:45-23:00 10 May: was not online And now question... How would you store information to implement such timelines? How would you query/calculate information about periods of time when user was online? Additional information.. You cannot update information about offline users, only users who are "currently" online. Solution should be flexible: timeline information could be represented relating to any timezone. We should keep information only for last 7 days. Every user seen online is automatically getting his own identifier in our database. Uff.. it was really hard for me to write it because my English is pretty bad, but I hope my question will be clear for you. Thank you.

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  • Pong: How does the paddle know where the ball will hit?

    - by Roflcoptr
    After implementing Pacman and Snake I'm implementing the next very very classic game: Pong. The implementation is really simple, but I just have one little problem remaining. When one of the paddle (I'm not sure if it is called paddle) is controlled by the computer, I have trouble to position it at the correct position. The ball has a current position, a speed (which for now is constant) and a direction angle. So I could calculate the position where it will hit the side of the computer controlled paddle. And so Icould position the paddle right there. But however in the real game, there is a probability that the computer's paddle will miss the ball. How can I implement this probability? If I only use a probability of lets say 0.5 that the computer's paddle will hit the ball, the problem is solved, but I think it isn't that simple. From the original game I think the probability depends on the distance between the current paddle position and the position the ball will hit the border. Does anybody have any hints how exactly this is calculated?

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  • Google Maps API - Get points along route between lat/long

    - by user311374
    I have a web site that I am trying to get completed and I need to have the user click points on a map and then work out the route on the roads between the two points. So the user clicks the first point on 1st street, and then clicks another point on 4th street, and the map will find the best way to get there and plot the route on the map. I am assuming this can be done using directions and parse it up, but I have been searching for an hour now and can't find what I am looking for (maybe bad search terms). I need to be able to plot the map manually (?) so I can calculate the distance, etc... of the route as the user continues to click. The site that is in beta is http://www.RunMyRoute.com/UserRoutes/Create and you can see I am trying to create running routes. I want the user to have the option for the route to follow the roads versus just a straight line between two points on the map. Any help on this would be great! Simon.

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  • The algorithm used to generate recommendations in Google News?

    - by Siddhant
    Hi everyone. I'm study recommendation engines, and I went through the paper that defines how Google News generates recommendations to users for news items which might be of their interest, based on collaborative filtering. One interesting technique that they mention is Minhashing. I went through what it does, but I'm pretty sure that what I have is a fuzzy idea and there is a strong chance that I'm wrong. The following is what I could make out of it :- Collect a set of all news items. Define a hash function for a user. This hash function returns the index of the first item from the news items which this user viewed, in the list of all news items. Collect, say "n" number of such values, and represent a user with this list of values. Based on the similarity count between these lists, we can calculate the similarity between users as the number of common items. This reduces the number of comparisons a lot. Based on these similarity measures, group users into different clusters. This is just what I think it might be. In Step 2, instead of defining a constant hash function, it might be possible that we vary the hash function in a way that it returns the index of a different element. So one hash function could return the index of the first element from the user's list, another hash function could return the index of the second element from the user's list, and so on. So the nature of the hash function satisfying the minwise independent permutations condition, this does sound like a possible approach. Could anyone please confirm if what I think is correct? Or the minhashing portion of Google News Recommendations, functions in some other way? I'm new to internal implementations of recommendations. Any help is appreciated a lot. Thanks!

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  • C function changes behaviour depending on whether it has a call to printf in it

    - by Daniel
    I have a function that processes some data and finds the threshold that classifies the data with the lowest error. It looks like this: void find_threshold(FeatureVal* fvals, sampledata* data, unsigned int num_samples, double* thresh, double* err, int* pol) { //code to calculate minThresh, minErr, minPol omitted printf("minThresh: %f, minErr: %f, minPol: %d\n", minThresh, minErr, minPol); *thresh = minThresh; *err = minErr; *pol = minPol; } Then in my test file I have this: void test_find_threshold() { //code to set up test data omitted find_threshold(fvals, sdata, 6, &thresh, &err, &pol); printf("Expected 5 got %f\n", thresh); assert(eq(thresh, 5.0)); printf("Expected 1 got %d\n", pol); assert(pol == 1); printf("Expected 0 got %f\n", err); assert(eq(err, 0.0)); } This runs and the test passes with the following output: minThresh: 5.000000, minErr: 0.000000, minPol: 1 Expected 5 got 5.000000 Expected 1 got 1 Expected 0 got 0.000000 However if I remove the call to printf() from find_threshold, suddenly the test fails! Commenting out the asserts so that I can see what gets returned, the output is: Expected 5 got -15.000000 Expected 1 got -1 Expected 0 got 0.333333 I cannot make any sense of this whatsoever.

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  • mySQL Efficiency Issue - How to find the right balance of normalization...?

    - by Foo
    I'm fairly new to working with relational databases, but have read a few books and know the basics of good design. I'm facing a design decision, and I'm not sure how to continue. Here's a very over simplified version of what I'm building: People can rate photos 1-5, and I need to display the average votes on the picture while keeping track of the individual votes. For example, 12 people voted 1, 7 people voted 2, etc. etc. The normalization freak of me initially designed the table structure like this: Table pictures id* | picture | userID | Table ratings id* | pictureID | userID | rating With all the foreign key constraints and everything set as they shoudl be. Every time someone rates a picture, I just insert a new record into ratings and be done with it. To find the average rating of a picture, I'd just run something like this: SELECT AVG(rating) FROM ratings WHERE pictureID = '5' GROUP by pictureID Having it setup this way lets me run my fancy statistics to. I can easily find who rated a certain picture a 3, and what not. Now I'm thinking if there's a crapload of ratings (which is very possible in what I'm really designing), finding the average will became very expensive and painful. Using a non-normalized version would seem to be more efficient. e.g.: Table picture id | picture | userID | ratingOne | ratingTwo | ratingThree | ratingFour | ratingFive To calculate the average, I'd just have to select a single row. It seems so much more efficient, but so much more uglier. Can someone point me in the right direction of what to do? My initial research shows that I have to "find the right balance", but how do I go about finding that balance? Any articles or additional reading information would be appreciated as well. Thanks.

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  • Display real time years, months, weeks and days between 2 days in JavaScript

    - by alex
    This is what I've coded it up, and it appears to work. window.onload = function() { var currentSpan = document.getElementById('current'); var minute = 60000, hour = minute * 60, day = hour * 24, week = day * 7, month = week * 4, year = day * 365; var start = new Date(2009, 6, 1); setInterval(function() { var now = new Date(); var difference = now - start; var years = Math.floor(difference / year), months = Math.floor((difference - (years * year)) / month), weeks = Math.floor((difference - (months * month + years * year)) / week), days = Math.floor((difference - (weeks * week + months * month + years * year)) / day); currentSpan.innerHTML = 'Since has passed: ' + years + ' years, ' + months + ' months, ' + weeks + ' weeks and ' + days + ' days'; }, 500); }; This seems to update my span fine, and all the numbers look correct. However, the code looks quite ugly. Do I really need to set up faux constants like that, and then do all that math to calculate what I want? It's been a while since I've worked with the Date object. Is this the best way to do this?

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  • Complex derived attributes in Django models

    - by rabidpebble
    What I want to do is implement submission scoring for a site with users voting on the content, much like in e.g. reddit (see the 'hot' function in http://code.reddit.com/browser/sql/functions.sql). My submission model currently keeps track of up and down vote totals. Currently, when a user votes I create and save a related Vote object and then use F() expressions to update the Submission object's voting totals. The problem is that I want to update the score for the submission at the same time, but F() expressions are limited to only simple operations (it's missing support for log(), date_part(), sign() etc.) From my limited experience with Django I can see 4 options here: extend F() somehow (haven't looked at the code yet) to support the missing SQL functions; this is my preferred option and seems to fit within the Django framework the best define a scoring function (much like reddit's 'hot' function) in my database, and have Django use the value of that function for the value of the score field; as far as I can tell, #2 is not possible wrap my two step voting process in a suitably isolated transaction so that I can calculate the voting totals in Python and then update the Submission's voting totals without fear that another vote against the submission could be added/changed in the meantime; I'm hesitant to take this route because it seems overly complex - what is a "suitably isolated transaction" in this case anyway? use raw SQL; I would prefer to avoid this entirely -- what's the point of an ORM if I have to revert to SQL for such a common use case as this! (Note that this coming from somebody who loves sprocs, but is using Django for ease of development.) Before I embark on this mission to extend F() (which I'm not sure is even possible), am I about to reinvent the wheel? Is there a more standard way to do this? It seems like such a common use case and yet in an hour of searching I have yet to find a common solution...

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  • Obtaining Current Fiscal Year from Hierarchy with MDX

    - by Robert Iver
    I'm building a report in Reporting Services 2005 based on a SSAS 2005 cube. The basic idea of the report is that they want to see sales for this fiscal year to date vs. last year sales year to date. It sounds simple, but being that this is my first "real" report based on SSAS, I'm having a hell of a time. First, how would one calculate the current fiscal year, quarter, or month. I have a Fiscal Date Hierarchy with all that information in it, but I can't figure out how to say: "Based on today's date, find the current fiscal year, quarter, and month." My second, but slightly smaller problem, is getting last years sales vs. this years sales. I have seen MANY examples on how to do this, but they all assume that you select the date manually. Since this is a report and will run pretty much on it's own, I need a way to insert the "current" fiscal year, quarter, and month into the PERIODSTODATE or PARALLELPERIOD functions to get what I want. So, I'm begging for your help on this one. I have to have this report done by tomorrow monring and I'm beginning to freak out a bit. Thanks in advance.

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  • rotate an image aroound a point

    - by Girish
    Hi all, I have an image which is of rectangular dimension, eg 30 x 60 pixels I want to rotate this image around the bottom center of the image, i.e i want to set the pivot in the above example as (15, 60 )pixel. I am using a drawble and matrix to get this done, whatever i try i always end up rotating around center of the image. Code is : Bitmap bitmapOrg = BitmapFactory.decodeFile("/sdcard/DCIM/2010-06-01_15-32-42_821.jpg"); // float angle = (angle + 10.0f)%360.0f; if(null !=bitmapOrg) { int width = bitmapOrg.getWidth(); int height = bitmapOrg.getHeight(); int newWidth = 15; int newHeight = 15; // calculate the scale - in this case = 0.4f float scaleWidth = ((float) newWidth) / width; float scaleHeight = ((float) newHeight) / height; /* Canvas c = new Canvas(bitmapOrg); float px = ; float py; c.rotate(angle, px, py)*/ // createa matrix for the manipulation Matrix matrix = new Matrix(); // resize the bit map matrix.postScale(scaleWidth, scaleHeight); // rotate the Bitmap // matrix.postRotate(45); // recreate the new Bitmap Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0, width, height, matrix, true); // make a Drawable from Bitmap to allow to set the BitMap // to the ImageView, ImageButton or what ever BitmapDrawable bmd = new BitmapDrawable(resizedBitmap); ImageView imageView = new ImageView(this); // set the Drawable on the ImageView imageView.setImageDrawable(bmd); // center the Image imageView.setScaleType(ScaleType.CENTER); // imageView.layout(100, 300, 0, 0); // linLayout.addView(imageView); // add ImageView to the Layout linLayout.addView(imageView, new AbsoluteLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 10, 30 ) ); can anyone let me know how to get this rectified?

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  • What is the best way to get an audio file duration in Android?

    - by Gilead
    Hi! I'm using a SoundPool [ 1 ] to play audio clips in my app. All is fine but I need to know when the clip playback has finished. At the moment I track it in my app by obtaining the duration of each clip using a MediaPlayer [ 2 ] instance. That works fine but it looks wasteful to load each file twice, just to get the duration. I could roughly calculate the duration myself knowing the length of the file (available from the AssetFileDescriptor [ 3 ]) but I'd still need to know the sample rate and the number of channels. I see two potential solutions to that problem: Figuring out when a clip has finished playing (doesn't seem to be possible with SoundClip). Having a class which could load just the header of an audio file and give me the sample rate/number of channels (and, ideally, the sample count to get the exact duration). Any suggestions? Thanks, Max The code I'm using at the moment (works fine but is rather heavy for the purpose): String[] fileNames = ... MediaPlayer mp = new MediaPlayer(); for (String fileName : fileNames) { AssetFileDescriptor d = context.getAssets().openFd(fileName); mp.reset(); mp.setDataSource(d.getFileDescriptor(), d.getStartOffset(), d.getLength()); mp.prepare(); int duration = mp.getDuration(); // ... } On a side note, this question has already been asked [ 4 ] but got no answers.

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  • Validation for Alert dialog

    - by Hossam
    Hi Everyone, Im working in a game and when the player finished the level , Im asking the Player to enter his name on EditText in Alert Dialog : AlertDialog.Builder builder = new Builder(this); LayoutInflater inflater = getLayoutInflater(); // Inflate and set the layout for the dialog // Pass null as the parent view because its going in the dialog layout builder.setView(inflater.inflate(R.layout.dialog_name, null)) // Add action buttons .setPositiveButton(R.string.alertName, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int id) { playerText = (EditText) ((AlertDialog)dialog).findViewById(R.id.username); if(playerText.getText() != null && playerText.getText().length() != 0) Helper.currentPlayer.setName(playerText.getText().toString()); //calculate the score // save in data base PlayerDataSource playerDS = new PlayerDataSource(getApplicationContext()); playerDS.open(); Helper.currentPlayer = playerDS.createPlayer(Helper.currentPlayer.getName(), Helper.currentPlayer.getScore(), Helper.currentPlayer.levels, Helper.currentPlayer.times, LanguageHelper.div); playerDS.close(); saveStmc(); mainScene.setChildScene(choicesMenu, false, true, true); } }) .setTitle("Please Enter Your name") .setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { } }); alert = builder.create(); When the Player enters his name and press OK (Positive button) I will check in database if the name exists or not, if the name is exist : show Toast and not dismiss the alert to write another name. How to do that?

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  • verilog / systemverilog -- What is the behavior of blocking statements across two always blocks?

    - by miles.sherman
    I am wondering about the behavior of the below code. There are two always blocks, one is combinational to calculate the next_state signal, the other is sequential which will perform some logic and determine whether or not to shutdown the system. It does this by setting the shutdown_now signal high and then calling state <= next_state. My question is if the conditions become true that the shutdown_now signal is set (during clock cycle n) in a blocking manner before the state <= next_state line, will the state during clock cycle n+1 be SHUTDOWN or RUNNING? In other words, does the shutdown_now = 1'b1 line block across both state machines since the state signal is dependent on it through the next_state determination? enum {IDLE, RUNNING, SHUTDOWN} state, next_state; logic shutdown_now; // State machine (combinational) always_comb begin case (state) IDLE: next_state <= RUNNING; RUNNING: next_state <= shutdown ? SHUTDOWN : RUNNING; SHUTDOWN: next_state <= SHUTDOWN; default: next_state <= SHUTDOWN; endcase end // Sequential Behavior always_ff @ (posedge clk) begin // Some code here if (/*some condition) begin shutdown_now = 1'b0; end else begin shutdown_now = 1'b1; end state <= next_state; end

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  • Reasons for & against a Database

    - by dbemerlin
    Hi, i had a discussion with a coworker about the architecture of a program i'm writing and i'd like some more opinions. The Situation: The Program should update at near-realtime (+/- 1 Minute). It involves the movement of objects on a coordinate system. There are some events that occur at regular intervals (i.e. creation of the objects). Movements can change at any time through user input. My solution was: Build a server that runs continously and stores the data internally. The server dumps a state-of-the-program at regular intervals to protect against powerfailures and/or crashes. He argued that the program requires a Database and i should use cronjobs to update the data. I can store movement information by storing startpoint, endpoint and speed and update the position in the cronjob (and calculate collisions with other objects there) by calculating direction and speed. His reasons: Requires more CPU & Memory because it runs constantly. Powerfailures/Crashes might destroy data. Databases are faster. My reasons against this are mostly: Not very precise as events can only occur at full minutes (wouldn't be that bad though). Requires (possibly costly) transformation of data on every run from relational data to objects. RDBMS are a general solution for a specialized problem so a specialized solution should be more efficient. Powerfailures (or other crashes) can leave the Data in an undefined state with only partially updated data unless (possibly costly) precautions (like transactions) are taken. What are your opinions about that? Which arguments can you add for any side?

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  • calculating min and max of 2-D array in c

    - by m2010
    This program to calculate sum,min and max of array elements Max value is the problem, it is always not true. void main(void) { int degree[3][2]; int min_max[][]; int Max=min_max[0][0]; int Min=min_max[0][0]; int i,j; int sum=0; clrscr(); for(i=0;i<3;i++) { for(j=0;j<2;j++) { printf("\n enter degree of student no. %d in subject %d:",i+1,j+1); scanf("%d",&degree[i][j]); } } for(i=0;i<3;i++) { for(j=0;j<2;j++) { printf("\n Student no. %d degree in subject no. %d is %d",i+1,j+1,degree[i][j]); } } for(i=0;i<3;i++) { sum=0; for(j=0;j<2;j++) { sum+=degree[i][j]; } printf("\n sum of degrees of student no. %d is %d",i+1,sum); min_max[i][j]=sum; if(min_max[i][j] <Min) { Min=min_max[i][j]; } else if(min_max[i][j]>Max) { Max=min_max[i][j]; } } printf("\nThe minimum sum of degrees of student no. %d is %d",i,Min); printf("\nThe maximum sum of degrees of student no. %d is %d",i,Max); getch(); }

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  • Computing complex math equations in python

    - by dassouki
    Are there any libraries or techniques that simplify computing equations ? Take the following two examples: F = B * { [ a * b * sumOf (A / B ''' for all i ''' ) ] / [ sumOf(c * d * j) ] } where: F = cost from i to j B, a, b, c, d, j are all vectors in the format [ [zone_i, zone_j, cost_of_i_to_j], [..]] This should produce a vector F [ [1,2, F_1_2], ..., [i,j, F_i_j] ] T_ij = [ P_i * A_i * F_i_j] / [ SumOf [ Aj * F_i_j ] // j = 1 to j = n ] where: n is the number of zones T = vector [ [1, 2, A_1_2, P_1_2], ..., [i, j, A_i_j, P_i_j] ] F = vector [1, 2, F_1_2], ..., [i, j, F_i_j] so P_i would be the sum of all P_i_j for all j and Aj would be sum of all P_j for all i I'm not sure what I'm looking for, but perhaps a parser for these equations or methods to deal with multiple multiplications and products between vectors? To calculate some of the factors, for example A_j, this is what i use from collections import defaultdict A_j_dict = defaultdict(float) for A_item in TG: A_j_dict[A_item[1]] += A_item[3] Although this works fine, I really feel that it is a brute force / hacking method and unmaintainable in the case we want to add more variables or parameters. Are there any math equation parsers you'd recommend? Side Note: These equations are used to model travel. Currently I use excel to solve a lot of these equations; and I find that process to be daunting. I'd rather move to python where it pulls the data directly from our database (postgres) and outputs the results into the database. All that is figured out. I'm just struggling with evaluating the equations themselves. Thanks :)

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  • Can an interface define the signature of a c#-constructor

    - by happyclicker
    I have a .net-app that provides a mechanism to extend the app with plugins. Each plugin must implement a plugin-interface and must provide furthermore a constructor that receives one parameter (a resource context). During the instantiation of the plugin-class I look via reflection, if the needed constructor exists and if yes, I instantiate the class (via Reflection). If the constructor does not exists, I throw an exception that says that the plugin not could be created, because the desired constructor is not available. My question is, if there is a way to declare the signature of a constructor in the plugin-interface so that everyone that implements the plugin-interface must also provide a constructor with the desired signature. This would ease the creation of plugins. I don’t think that such a possibility exists because I think such a feature falls not in the main purpose for what interfaces were designed for but perhaps someone knows a statement that does this, something like: public interface IPlugin { ctor(IResourceContext resourceContext); int AnotherPluginFunction(); } I want to add that I don't want to change the constructor to be parameterless and then set the resource-context through a property, because this will make the creation of plugins much more complicated. The persons that write plugins are not persons with deep programming experience. The plugins are used to calculate statistical data that will be visualized by the app.

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  • Using Rails Helper Methods within ActionRecord Queries?

    - by Pygmalion
    I have a table of events (in a sqlite3 database for what it's worth) with a column called "when" that contains a timestamp detailing precisely when the event that particular row denotes is set to occur. Right now, I have @events = Event.find(:all) in my controller and I am using template helper methods to calculate where to place each event on my display page based on the day of the week it occurs on. For example: <% if(event.when.wday == 6) %> # DO SOMETHING <% end %> I want to abstract this logic to the controller however. My idea was to do the following: @thursday_events = Event.find(:all, :conditions => ["when.wday=4"]) Obviously (I guess?) this didn't work. Throwing the error "SQLite3::SQLException: near "when": syntax error: SELECT * FROM "events" WHERE (when.wday=4)". I'm assuming this is because I tried to use a helper method within a find condition but I don't know a better way to do this. Any advice? Thanks!

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  • How to allow users to define financial formulas in a C# app

    - by Peter Morris
    I need to allow my users to be able to define formulas which will calculate values based on data. For example //Example 1 return GetMonetaryAmountFromDatabase("Amount due") * 1.2; //Example 2 return GetMonetaryAmountFromDatabase("Amount due") * GetFactorFromDatabase("Discount"); I will need to allow / * + - operations, also to assign local variables and execute IF statements, like so var amountDue = GetMonetaryAmountFromDatabase("Amount due"); if (amountDue > 100000) return amountDue * 0.75; if (amountDue > 50000) return amountDue * 0.9; return amountDue; The scenario is complicated because I have the following structure.. Customer (a few hundred) Configuration (about 10 per customer) Item (about 10,000 per customer configuration) So I will perform a 3 level loop. At each "Configuration" level I will start a DB transaction and compile the forumlas, each "Item" will use the same transaction + compiled formulas (there are about 20 formulas per configuration, each item will use all of them). This further complicates things because I can't just use the compiler services as it would result in continued memory usage growth. I can't use a new AppDomain per each "Configuration" loop level because some of the references I need to pass cannot be marshalled. Any suggestions?

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  • How to get levels for Fry Graph readability formula?

    - by Vic
    Hi, I'm working in an application (C#) that applies some readability formulas to a text, like Gunning-Fog, Precise SMOG, Flesh-Kincaid. Now, I need to implement the Fry-based Grade formula in my program, I understand the formula's logic, pretty much you take 3 100-words samples and calculate the average on sentences per 100-words and syllables per 100-words, and then, you use a graph to plot the values. Here is a more detailed explanation on how this formula works. I already have the averages, but I have no idea on how can I tell my program to "go check the graph and plot the values and give me a level." I don't have to show the graph to the user, I only have to show him the level. I was thinking that maybe I can have all the values in memory, divided into levels, for example: Level 1: values whose sentence average are between 10.0 and 25+, and whose syllables average are between 108 and 132. Level 2: values whose sentence average are between 7.7 and 10.0, and .... so on But the problem is that so far, the only place in which I have found the values that define a level, are in the graph itself, and they aren't too much accurate, so if I apply the approach commented above, trying to take the values from the graph, my level estimations would be too much imprecise, thus, the Fry-based Grade will not be accurate. So, maybe any of you knows about some place where I can find exact values for the different levels of the Fry-based Grade, or maybe any of you can help me think in a way to workaround this. Thanks

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  • magento, making a grouped product show on sale based on product children prices

    - by thrice801
    Hi, Question regarding Magento and sale items. So I have to use grouped items to link multiple items which are the same style but different colors, these are the items I have showing on my search results/category pages. - I am trying to figure out how I can make the master sku, show as on sale, when the children items are marked on sale. I am able to make it show up on the product page, but anytime I have tried calling any of the getchildren methods outside of grouped.phtml, I have failed, horribly. I think I worked on that method for probably 36 hours unsuccessfully calling it from any other page. So, I thought I would ask here. Does anyone know how I could call the getchildskus or whatever it is method, from the category page, so that I can do something like, for each child product, compare sale price with active price, if there is a difference, calculate the percentage off, and display the largest difference as "ON SALE, UP TO 30% OFF!", or whatever it may be? Any help would be much appreciated. (oh, and I cant set a price on the main group sku, I sell sunglasses and watches mainly and many times a different color will differ in price quite significantly.)

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  • Stack usage with MMX intrinsics and Microsoft C++

    - by arik-funke
    I have an inline assembler loop that cumulatively adds elements from an int32 data array with MMX instructions. In particular, it uses the fact that the MMX registers can accommodate 16 int32s to calculate 16 different cumulative sums in parallel. I would now like to convert this piece of code to MMX intrinsics but I am afraid that I will suffer a performance penalty because one cannot explicitly intruct the compiler to use the 8 MMX registers to accomulate 16 independent sums. Can anybody comment on this and maybe propose a solution on how to convert the piece of code below to use intrinsics? == inline assembler (only part within the loop) == paddd mm0, [esi+edx+8*0] ; add first & second pair of int32 elements paddd mm1, [esi+edx+8*1] ; add third & fourth pair of int32 elements ... paddd mm2, [esi+edx+8*2] paddd mm3, [esi+edx+8*3] paddd mm4, [esi+edx+8*4] paddd mm5, [esi+edx+8*5] paddd mm6, [esi+edx+8*6] paddd mm7, [esi+edx+8*7] ; add 15th & 16th pair of int32 elements esi points to the beginning of the data array edx provides the offset in the data array for the current loop iteration the data array is arranged such that the elements for the 16 independent sums are interleaved.

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