Search Results

Search found 6094 results on 244 pages for 'double gras'.

Page 57/244 | < Previous Page | 53 54 55 56 57 58 59 60 61 62 63 64  | Next Page >

  • How can I work around the fact that in C++, sin(M_PI) is not 0?

    - by Adam Doyle
    In C++, const double Pi = 3.14159265; cout << sin(Pi); // displays: 3.58979e-009 it SHOULD display the number zero I understand this is because Pi is being approximated, but is there any way I can have a value of Pi hardcoded into my program that will return 0 for sin(Pi)? (a different constant maybe?) In case you're wondering what I'm trying to do: I'm converting polar to rectangular, and while there are some printf() tricks I can do to print it as "0.00", it still doesn't consistently return decent values (in some cases I get "-0.00") The lines that require sin and cosine are: x = r*sin(theta); y = r*cos(theta); BTW: My Rectangular - Polar is working fine... it's just the Polar - Rectangular Thanks! edit: I'm looking for a workaround so that I can print sin(some multiple of Pi) as a nice round number to the console (ideally without a thousand if-statements) edit: In case anyone's curious, this was what I landed on: double sin2(double theta) // in degrees { double s = sin(toRadians(theta)); if (fabs(s - (int)s) < 0.000001) { return floor(s + 0.5); } return s; } where toRadians() is a macro that converts to radians

    Read the article

  • Custom QAbstractGraphicsShapeItem very slow in Qt Jambi

    - by Mene
    I try to implement an own QAbstractGraphicsShapeItem in Qt Jambi (4.5) but as soon as I implement a custom class (rather than use e.g. QGraphicsEllipseItem) the rendering speed drops by about on order of magnitude. If looked in the original Code of QGraphicsEllipseItem and it seems to do basicly the same. class Circle extends QAbstractGraphicsShapeItem { final private QRectF rect = new QRectF(); public final void setRect(double x, double y, double w, double h) { QRectF newRect = new QRectF(x, y, w, h); if (!newRect.equals(rect)) { prepareGeometryChange(); this.rect.setX(x); this.rect.setY(y); this.rect.setWidth(w); this.rect.setHeight(h); this.update(rect); } } @Override public final QRectF boundingRect() { return rect; } QPainterPath shape; @Override public final QPainterPath shape() { if (shape == null) { QPainterPath path = new QPainterPath(); path.addEllipse(rect); QPainterPathStroker stroker = new QPainterPathStroker(); QPen pen = this.pen(); stroker.setCapStyle(pen.capStyle()); stroker.setWidth(pen.widthF()); shape = stroker.createStroke(path); } return shape; } @Override public final void paint(QPainter painter, QStyleOptionGraphicsItem option, QWidget widget) { painter.setPen(this.pen()); painter.setBrush(this.brush()); painter.drawEllipse(this.rect); } } I need to render a lot of objects and they are mostly moving, so speed is essential. Anyone knows how to speed this up? I underestand that Java might be slower then the nativ code in the library. But the code in the paint method seems not to be the problem, since commenting it out doesn't change the speed notably.

    Read the article

  • how do I make a portable isnan/isinf function.

    - by monkeyking
    I've been using isinf,isnan functions on linux platforms which worked perfectly. But this didn't work on osx, so I decided to use std::isinf std::isnan which works on both linux and osx. But the intel compiler doesn't recognize it, and I guess its a bug in the intel compiler according to http://software.intel.com/en-us/forums/showthread.php?t=64188 So now I just want to avoid the hassle and define my own isinf,isnan implementation. Does anyone know how this could be done Thanks edit: I ended up doing this in my sourcecode for making isinf/isnan working #include <iostream> #include <cmath> #ifdef __INTEL_COMPILER #include <mathimf.h> #endif int isnan_local(double x) { #ifdef __INTEL_COMPILER return isnan(x); #else return std::isnan(x); #endif } int isinf_local(double x) { #ifdef __INTEL_COMPILER return isinf(x); #else return std::isinf(x); #endif } int myChk(double a){ std::cerr<<"val is: "<<a <<"\t"; if(isnan_local(a)) std::cerr<<"program says isnan"; if(isinf_local(a)) std::cerr<<"program says isinf"; std::cerr<<"\n"; return 0; } int main(){ double a = 0; myChk(a); myChk(log(a)); myChk(-log(a)); myChk(0/log(a)); myChk(log(a)/log(a)); return 0; }

    Read the article

  • Can't get recursive function to work in Java

    - by Ahmed Salah
    I read docs about java recorsion and I thought I have understood it, but when I try to use it in the following example, it does not work as expected. I a class account, which has amount and can have forther subAccount. I would have implemented one method getSum, which has to return the summ of the amount of the account and amount of all of its subaccount. In the following code, the call of the method getSumm() should return 550, but it behaves strange. can somebody help please? public class Balance{ ArrayList<Balance> subAccounts = new ArrayList<Balance>(); String accountID = null; Double amount = null; double result=0; public double getSum(ArrayList<Balance> subAccounts){ if(subAccounts !=null && subAccounts.size()>0){ for (int i = 0; i < subAccounts.size(); i++) { result = result + getSum(subAccounts.get(i).subAccounts); } } else { return amount; } return result; } public static void main(String[] args) { Balance bs1 = new Balance(); Balance bs2 = new Balance(); Balance bs3 = new Balance(); bs1.amount=100.0; bs2.amount=150.0; bs3.amount=300.0; ArrayList<Balance> subAccounts1 = new ArrayList<Balance>(); bs2.subAccounts=null; bs3.subAccounts=null; subAccounts1.add(bs2); subAccounts1.add(bs3); bs1.subAccounts=subAccounts1; double sum= bs1.getSum(subAccounts1); System.out.println(sum); } }

    Read the article

  • correct format for function prototype

    - by yCalleecharan
    Hi, I'm writing to a text file using the following declaration: void create_out_file(char file_name[],long double *z1){ FILE *out; int i; if((out = fopen(file_name, "w+")) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < ARRAY_SIZE; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } Where z1 is an long double array of length ARRAY_SIZE. The calling function is: create_out_file("E:/first67/jz1.txt", z1); I defined the prototype as: void create_out_file(char file_name[], long double z1[]); which I'm putting before "int main" but after the preprocessor directives. My code works fine. I was thinking of putting the prototype as void create_out_file(char file_name[],long double *z1). Is this correct? *z1 will point to the first array element of z1. Is my declaration and prototype good programming practice? Thanks a lot...

    Read the article

  • error C2512 in precompiled header file?

    - by SoloMael
    I'm having a ridiculously strange problem. When I try to run the program below, there's an error message that says: "error C2512: 'Record' : no appropriate default constructor available". And when I double-click it, it directs me to a precompiled read-only header file named "xmemory0". Do they expect me to change a read-only file? Here's the segment of code in the file it directs me to: void construct(_Ty *_Ptr) { // default construct object at _Ptr ::new ((void *)_Ptr) _Ty(); // directs me to this line } Here's the program: #include <iostream> #include <vector> #include <string> using namespace std; const int NG = 4; // number of scores struct Record { string name; // student name int scores[NG]; double average; // Calculate the average // when the scores are known Record(int s[], double a) { double sum = 0; for(int count = 0; count != NG; count++) { scores[count] = s[count]; sum += scores[count]; } average = a; average = sum / NG; } }; int main() { // Names of the class string names[] = {"Amy Adams", "Bob Barr", "Carla Carr", "Dan Dobbs", "Elena Evans"}; // exam scores according to each student int exams[][NG]= { {98, 87, 93, 88}, {78, 86, 82, 91}, {66, 71, 85, 94}, {72, 63, 77, 69}, {91, 83, 76, 60}}; vector<Record> records(5); return 0; }

    Read the article

  • C#'s equivalent to VB.Net's DirectCast?

    - by Collin Sauve
    This has probably been asked before, but if it has, I can't find it. Does C# have an equivalent to VB.Net's DirectCast? I am aware that it has () casts and the 'as' keyword, but those line up to CType and TryCast. To be clear, these keywords do the following; CType/() casts: If it is already the correct type, cast it, otherwise look for a type converter and invoke it. If no type converter is found, throw an InvalidCastException. TryCast/"as" keyword: If it is the correct type, cast it, otherwise return null. DirectCast: If it is the correct type, cast it, otherwise throw an InvalidCastException. EDIT: After I have spelled out the above, some people have still responded that () is equivalent, so I will expand further upon why this is not true. DirectCast only allows for either Narrowing or Widening conversions on inheritance tree, it does not support conversions across different branches like () does. ie: C#, this compiles and runs: //This code uses a type converter to go across an inheritance tree double d = 10; int i = (int)d; VB.Net, this does NOT COMPILE 'Direct cast can only go up or down a branch, never across to a different one. Dim d as Double= 10 Dim i as Integer = DirectCast(d, Integer) The equivalent in VB.Net to my C# code is CType: 'This compiles and runs Dim d as Double= 10 Dim i as Integer = CType(d, Integer) (Edit again, I was originally using strings, I changed it to double... sorry)

    Read the article

  • Constraining to parent container with MouseDragElementBehavior

    - by anonymous
    Hi all, I just had a question regarding constraining a control's drag and drop movement to its parent canvas. I tried using the ConstrainToParentBounds property on the MouseDragElementBehavior, however, when this is used the drag must be done really slowly or the movement of the control is choppy or stops altogether. So I am attempting to implement my own boundary constraints. I seem to be running into difficulty though. I am still using the MouseDragElementBehavior but am attempting to supplement it by also handling mouseleftbuttondown, mousemove, mouseleftbuttonup events. I know that these are working (haven't been overridden by the MouseDragElementBehavior) as I have tested them using other methods. I will post my current code below: private void Control_MouseMove(object sender, MouseEventArgs e) { MyControl mc = (MyControl)sender; Canvas canvas = (Canvas)mc.parent; GeneralTransform ct = canvas.TransformToVisual(Application.Current.RootVisual as UIElement; Point canvas_offset = ct.Transform(new Point(0,0)); double canvasTop = canvas_offset.Y; double canvasLeft = canvas_offset.X; GeneralTransform gt = mc.TransformToVisual(Application.Current.RootVisual as UIElement); Point offset = gt.Transform(new Point(0,0)); double controlTop = offset.Y; double controlLeft = offset.X; if(isMouseCaptured) { if(controlTop < canvasTop) { mc.Opacity = 1; //to test if conditions are being met, seems to indicate ok mc.setValue(Canvas.TopProperty, canvasTop); } if(controlLeft < canvasLeft) { mc.Opacity = 1; mc.setValue(Canvas.TopProperty, canvasTop); } } } This is what my code looks like at the moment (I realize there is nothing there for right/bottom). I've tried a bunch of different things at this point and none of them seem to give the desired result; the control's movement is still not constrained to the canvas. Any help/pointers would be greatly appreciated. Thanks!

    Read the article

  • Beginning Haskell: "not in scope" Unprecedented error

    - by user1071838
    So I just started learning Haskell, and this (http://learnyouahaskell.com) nifty book is giving a lot of help. So yesterday I wrote in a text file doubleMe x = x + x and saved it as double.hs. So after saving that I open up my command prompt, CD to the right folder, type in "ghci" to get haskell started, and then type in >doubleMe 5 10 and everything seems to work. Now today, I do the same thing and this happens (actual copy paste from command line) . . . C:\Users\myName\haskell>ghci GHCi, version 7.0.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude> :l double.hs [1 of 1] Compiling Main ( double.hs, interpreted ) Ok, modules loaded: Main. *Main> doubleMe 5 <interactive>:1:1: Not in scope: `doubleMe' So basically, everything was working fine, but now haskell can't find the function I wrote in double.hs. Can anyone tell what is going on? I'm pretty lost and confused. This is just a guess but does it have to do with *Main at all? Thanks for the help.

    Read the article

  • Hibernate design to speed up querying of large dataset

    - by paddydub
    I currently have the below tables representing a bus network mapped in hibernate, accessed from a Spring MVC based bus route planner I'm trying to make my route planner application perform faster, I load all the above tables into Lists to perform the route planner logic. I would appreciate if anyone has any ideas of how to speed my performace Or any suggestions of another method to approach this problem of handling a large set of data Coordinate Connections Table (INT,INT,INT, DOUBLE)( Containing 50,000 Coordinate Connections) ID, FROMCOORDID, TOCOORDID, DISTANCE 1 1 2 0.383657 2 1 17 0.173201 3 1 63 0.258781 4 1 64 0.013726 5 1 65 0.459829 6 1 95 0.458769 Coordinate Table (INT,DECIMAL, DECIMAL) (Containing 4700 Coordinates) ID , LAT, LNG 0 59.352669 -7.264341 1 59.352669 -7.264341 2 59.350012 -7.260653 3 59.337585 -7.189798 4 59.339221 -7.193582 5 59.341408 -7.205888 Bus Stop Table (INT, INT, INT)(Containing 15000 Stops) StopID RouteID COORDINATEID 1000100001 100 17 1000100002 100 18 1000100003 100 19 1000100004 100 20 1000100005 100 21 1000100006 100 22 1000100007 100 23 This is how long it takes to load all the data from each table: stop.findAll = 148ms, stops.size: 15670 Hibernate: select coordinate0_.COORDINATEID as COORDINA1_2_, coordinate0_.LAT as LAT2_, coordinate0_.LNG as LNG2_ from COORDINATES coordinate0_ coord.findAll = 51ms , coordinates.size: 4704 Hibernate: select coordconne0_.COORDCONNECTIONID as COORDCON1_3_, coordconne0_.DISTANCE as DISTANCE3_, coordconne0_.FROMCOORDID as FROMCOOR3_3_, coordconne0_.TOCOORDID as TOCOORDID3_ from COORDCONNECTIONS coordconne0_ coordinateConnectionDao.findAll = 238ms ; coordConnectioninates.size:48132 Hibernate Annotations @Entity @Table(name = "STOPS") public class Stop implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "STOPID") private int stopID; @Column(name = "ROUTEID", nullable = false) private int routeID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "COORDINATEID", nullable = false) private Coordinate coordinate; } @Table(name = "COORDINATES") public class Coordinate { @Id @GeneratedValue @Column(name = "COORDINATEID") private int CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Entity @Table(name = "COORDCONNECTIONS") public class CoordConnection { @Id @GeneratedValue @Column(name = "COORDCONNECTIONID") private int CoordinateID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "FROMCOORDID", nullable = false) private Coordinate fromCoordID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "TOCOORDID", nullable = false) private Coordinate toCoordID; @Column(name = "DISTANCE", nullable = false) private double distance; }

    Read the article

  • Compute weighted averages for large numbers

    - by Travis
    I'm trying to get the weighted average of a few numbers. Basically I have: Price - 134.42 Quantity - 15236545 There can be as few as one or two or as many as fifty or sixty pairs of prices and quantities. I need to figure out the weighted average of the price. Basically, the weighted average should give very little weight to pairs like Price - 100000000.00 Quantity - 3 and more to the pair above. The formula I currently have is: ((price)(quantity) + (price)(quantity) + ...)/totalQuantity So far I have this done: double optimalPrice = 0; int totalQuantity = 0; double rolling = 0; System.out.println(rolling); Iterator it = orders.entrySet().iterator(); while(it.hasNext()) { System.out.println("inside"); Map.Entry order = (Map.Entry)it.next(); double price = (Double)order.getKey(); int quantity = (Integer)order.getValue(); System.out.println(price + " " + quantity); rolling += price * quantity; totalQuantity += quantity; System.out.println(rolling); } System.out.println(rolling); return totalQuantity / rolling; The problem is I very quickly max out the "rolling" variable. How can I actually get my weighted average? Thanks!

    Read the article

  • C++ overide global operator comma gives error

    - by uray
    the second function gives error C2803 http://msdn.microsoft.com/en-us/library/zy7kx46x%28VS.80%29.aspx : 'operator ,' must have at least one formal parameter of class type. any clue? template<class T,class A = std::allocator<T>> class Sequence : public std::vector<T,A> { public: Sequence<T,A>& operator,(const T& a) { this->push_back(a); return *this; } Sequence<T,A>& operator,(const Sequence<T,A>& a) { for(Sequence<T,A>::size_type i=0 ; i<a.size() ; i++) { this->push_back(a.at(i)); } return *this; } }; //this works! template<typename T> Sequence<T> operator,(const T& a, const T&b) { Sequence<T> seq; seq.push_back(a); seq.push_back(b); return seq; } //this gives error C2803! Sequence<double> operator,(const double& a, const double& b) { Sequence<double> seq; seq.push_back(a); seq.push_back(b); return seq; }

    Read the article

  • Break a while loop without using If or Break

    - by Justin
    I need to create a program that uses while to find the volume of a cylinder. I need the while loop to break if the user inputs a negative value for the height. My code looks like this: double sentinel=1, h=1, v=0, r, count=0; // declares all variables needed final double PI=3.14159; boolean NotNegative=true; while(NotNegative){// && count==0){ // while both the height is positive AND the total times run is 0 System.out.print("Enter height (Use negative to exit): "); // has the user input the height h=Double.parseDouble(br.readLine()); sentinel=h; // save sentinel as the inputted height while(sentinel>0){ System.out.print("Enter radius: "); // have the user input the radius r=Double.parseDouble(br.readLine()); v=PI*(r*r)*h; // find the volume System.out.println("The volume is " + v); // print out the volume count++; // increase the count each time this runs NotNegative=true; sentinel=-1; } } Any help?

    Read the article

  • Problems sorting by date

    - by Nathan
    I'm attempting to only display data added to my database 24 hours ago or less. However, for some reason, the code I've written isn't working, and both entries in my database, one from 1 hour ago, one from 2 days ago, show up. Is there something wrong with my equation? Thanks! public void UpdateValues() { double TotalCost = 0; double TotalEarned = 0; double TotalProfit = 0; double TotalHST = 0; for (int i = 0; i <= Program.TransactionList.Count - 1; i++) { DateTime Today = DateTime.Now; DateTime Jan2013 = DateTime.Parse("01-01-2013"); //Hours since Jan12013 int TodayHoursSince2013 = Convert.ToInt32(Math.Round(Today.Subtract(Jan2013).TotalHours)); //7 int ItemHoursSince2013 = Program.TransactionList[i].HoursSince2013; //Equals 7176, and 7130 if (ItemHoursSince2013 - TodayHoursSince2013 <= 24) { TotalCost += Program.TransactionList[i].TotalCost; TotalEarned += Program.TransactionList[i].TotalEarned; TotalProfit += Program.TransactionList[i].TotalEarned - Program.TransactionList[i].TotalCost; TotalHST += Program.TransactionList[i].TotalHST; } } label6.Text = "$" + String.Format("{0:0.00}", TotalCost); label7.Text = "$" + String.Format("{0:0.00}", TotalEarned); label8.Text = "$" + String.Format("{0:0.00}", TotalProfit); label10.Text = "$" + String.Format("{0:0.00}", TotalHST); }

    Read the article

  • incremental way of counting quantiles for large set of data

    - by Gacek
    I need to count the quantiles for a large set of data. Let's assume we can get the data only through some portions (i.e. one row of a large matrix). To count the Q3 quantile one need to get all the portions of the data and store it somewhere, then sort it and count the quantile: List<double> allData = new List<double>(); foreach(var row in matrix) // this is only example. In fact the portions of data are not rows of some matrix { allData.AddRange(row); } allData.Sort(); double p = 0.75*allData.Count; int idQ3 = (int)Math.Ceiling(p) - 1; double Q3 = allData[idQ3]; Now, I would like to find a way of counting this without storing the data in some separate variable. The best solution would be to count some parameters od mid-results for first row and then adjust it step by step for next rows. Note: These datasets are really big (ca 5000 elements in each row) The Q3 can be estimated, it doesn't have to be an exact value. I call the portions of data "rows", but they can have different leghts! Usually it varies not so much (+/- few hundred samples) but it varies! This question is similar to this one: http://stackoverflow.com/questions/1058813/on-line-iterator-algorithms-for-estimating-statistical-median-mode-skewness But I need to count quantiles. ALso there are few articles in this topic, i.e.: http://web.cs.wpi.edu/~hofri/medsel.pdf http://portal.acm.org/citation.cfm?id=347195&dl But before I would try to implement these, I wanted to ask you if there are maybe any other, qucker ways of counting the 0.25/0.75 quantiles?

    Read the article

  • d2: assigning ranges/iterators to array slices

    - by modchan
    Consider following code: enum size = 16; double[size] arr1 = [...]; double[size] arr2 = [...]; process = (double x) { return (x + 1); }; arr2[] = map!(process)(arr1[]); // here I have trouble converting results of map back to my plain array. Problem applies not only to map, but also to take, repeat and all those fine tools from std.algorithm and std.range that operate on ranges. On this assignment, I get Error: cannot implicitly convert expression (map(arr1[])) of type Result to double[]. How can I evaluate range to array without using uint i = 0; foreach (x; map!(process)(arr1[])) { arr2[i] = x; i++; } ? Additionally, can someone please explain, why I must call map!(process)(arr1[]) instead of map!(process)(arr1) with static arrays? Shouldn't static arrays be compatible with dynamic for means of iteration, or I don't get something? Also, it seems that straightforward enumeration syntax foreach (index, item; sequence) does not work for ranges - are there workarounds? I guess the reason is the same as why ranges cannot be assigned to array slices.

    Read the article

  • Bing Map on Windows Phone - add click events to pushpins; display more details

    - by Will Gill
    I have a WP Phone app using a Bing Map control. I have an array of objects, and each object has a location. I iterate the array to place the pins on the map (see below). I have a touch event bound to each pin to allow the user to tap the pin to start an action. Now - I would like, on tap, to show information from the object that relates to that pin to be shown in a textbox. How can I retrieve the object from the array that corresponds to the pushpin that was tapped/clicked? foreach (wikiResult result in arrayResults) { double lat = double.Parse(result.Latitude, CultureInfo.InvariantCulture); double lng = double.Parse(result.Longitude, CultureInfo.InvariantCulture); statusTextBlock.Text = result.Latitude + " " + result.Longitude + " " + lat + " " + lng; GeoCoordinate d = new GeoCoordinate(lat, lng); Pushpin pin; pin = new Pushpin(); pin.Location = d; pin.Content = result.Name; pin.MouseLeftButtonUp += new MouseButtonEventHandler(pin1_MouseLeftButtonUp); myMap.Children.Add(pin); } void pin1_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) { //display the content from the object in a text box } Many thanks in advance!

    Read the article

  • How to use Comparator in Java to sort

    - by Dan
    I learned how to use the comparable but I'm having difficulty with the Comparator. I am having a error in my code: Exception in thread "main" java.lang.ClassCastException: New.People cannot be cast to java.lang.Comparable at java.util.Arrays.mergeSort(Unknown Source) at java.util.Arrays.sort(Unknown Source) at java.util.Collections.sort(Unknown Source) at New.TestPeople.main(TestPeople.java:18) Here is my code: import java.util.Comparator; public class People implements Comparator{ private int id; private String info; private double price; public People(int newid, String newinfo, double newprice){ setid(newid); setinfo(newinfo); setprice(newprice); } public int getid() { return id; } public void setid(int id) { this.id = id; } public String getinfo() { return info; } public void setinfo(String info) { this.info = info; } public double getprice() { return price; } public void setprice(double price) { this.price = price; } public int compare(Object obj1, Object obj2) { Integer p1 = ((People)obj1).getid(); Integer p2 = ((People)obj2).getid(); if (p1 p2 ){ return 1; } else if (p1 < p2){ return -1; } else return 0; } } import java.util.ArrayList; import java.util.Collections; public class TestPeople { public static void main(String[] args) { ArrayList peps = new ArrayList(); peps.add(new People(123, "M", 14.25)); peps.add(new People(234, "M", 6.21)); peps.add(new People(362, "F", 9.23)); peps.add(new People(111, "M", 65.99)); peps.add(new People(535, "F", 9.23)); Collections.sort(peps); for(int i=0;i I believe it has to do something with the casting in the compare method but I was playing around with it and still could not find the solution

    Read the article

  • Update a list of things without hitting every entry

    - by bobobobo
    I have a list in a database that the user should be able to order. itemname| order value (int) --------+--------------------- salad | 1 mango | 2 orange | 3 apples | 4 On load from the database, I simply order by order_value. By drag 'n drop, he should be able to move apples so that it appears at the top of the list.. itemname| order value (int) --------+--------------------- apples | 4 salad | 1 mango | 2 orange | 3 Ok. So now internally I have to update EVERY LIST ITEM! If the list has 20 or 100 items, that's a lot of updates for a simple drag operation. itemname| order value (int) --------+--------------------- apples | 1 salad | 2 mango | 3 orange | 4 I'd rather do it with only one update. One way I thought of is if "internal Order" is a double value. itemname| order value (double) --------+--------------------- salad | 1.0 mango | 2.0 orange | 3.0 apples | 4.0 SO after the drag n' drop operation, I assign apples has a value that is less than the item it is to appear in front of: itemname| order value (double) --------+--------------------- apples | 0.5 salad | 1.0 mango | 2.0 orange | 3.0 .. and if an item is dragged into the middle somewhere, its order_value is bigger than the one it appears after .. here I moved orange to be between salad and mango: itemname| order value (double) --------+--------------------- apples | 0.5 salad | 1.0 orange | 1.5 mango | 2.0 Any thoughts on better ways to do this?

    Read the article

  • Shortcut to create automatic properties using Visual Studio 2008/2010 or Resharper 5

    - by Piers Myers
    I have a class that contains a load of properties that contain results of some calculations e.g: public class Results { public double Result1 { get; set; } public double Result2 { get; set; } } In a different class I am doing calculations to populate the above properties, e.g: public class Calc { private Results Calc() { Results res = new Results(); res.Result1 = ... some calculation res.Result2 = ... some other calculation res.Result3 = ... // not yet defined in 'Results' class return res; } } When I am writing the Calc class, 'Result3' will be highlighted in red as it is not yet defined in the 'Results' class. Currently I am using the Resharper ALT-Enter shortcut, selecting "Create Property 'Result3'" which will create the following code int the 'Results' class: public double Result3 { get { throw new NotImplementedException(); } set { throw new NotImplementedException(); } } Which I need to manually change to: public double Result3 { get; set; } Then I use the CTRL-Shift-Backspace shortcut to take me back to the 'Calc' class. How can I easily create automatic properties in the 'Results' class if they are not yet defined directly from the 'Calc' class?

    Read the article

  • ScaleTransform transforms non-linearly

    - by Chris
    I am using scale transform to allow a user to resize a control. What happens though is that when you start to move the mouse the control jumps to a new size, and then scales oddly. The further you move your mouse from the starting location the larger the increase in size becomes. I expect its the way I calculate the scale to be applied. Here is the code: private void ResizeGrip_MouseDown(object sender, MouseButtonEventArgs e) { ResizeHandle.CaptureMouse(); //Get the initial coordinate cursor location on the window initBtmX = e.GetPosition(this).X; bottomResize = true; } private void ResizeGrip_MouseUp(object sender, MouseButtonEventArgs e) { bottomResize = false; ResizeHandle.ReleaseMouseCapture(); } private void ResizeGrip_MouseMove(object sender, MouseEventArgs e) { if( bottomResize == true) { //Get the new Y coordinate cursor location double newBtmX = e.GetPosition(this).X; //Get the smallest change between the initial and new cursor location double diffX = initBtmX - newBtmX; // Let our rectangle capture the mouse ResizeHandle.CaptureMouse(); double newWidth = e.GetPosition(this).X - diffX; double scaler = newWidth / ResizeContainer.ActualWidth; Console.WriteLine("newWidth: {0}, scalar: {1}", newWidth, scaler); if (scaler < 0.75 || scaler > 3) return; ScaleTransform scale = new ScaleTransform(scaler, scaler); ResizeContainer.LayoutTransform = scale; } }

    Read the article

  • C++, function pointer to the template function pointer

    - by Ian
    I am having a pointer to the common static method class MyClass { private: static double ( *pfunction ) ( const Object *, const Object *); ... }; pointing to the static method class SomeClass { public: static double getA ( const Object *o1, const Object *o2); ... }; Initialization: double ( *MyClass::pfunction ) ( const Object *o1, const Object *o2 ) = &SomeClass::getA; I would like to convert this pointer to the static template function pointer: template <class T> static T ( *pfunction ) ( const Object <T> *, const Object <T> *); //Compile error where: class SomeClass { public: template <class T> static double getA ( const Object <T> *o1, const Object <T> *o2); ... }; But there is some error... Thanks for your help...

    Read the article

  • How to call IronPython function from C#/F#?

    - by prosseek
    This is kind of follow up questions of http://stackoverflow.com/questions/2969194/integration-of-c-f-ironpython-and-ironruby In order to use C/C++ function from Python, SWIG is the easiest solution. The reverse way is also possible with Python C API, for example, if we have a python function as follows def add(x,y): return (x + 10*y) We can come up with the wrapper in C to use this python as follows. double Add(double a, double b) { PyObject *X, *Y, *pValue, *pArgs; double res; pArgs = PyTuple_New(2); X = Py_BuildValue("d", a); Y = Py_BuildValue("d", b); PyTuple_SetItem(pArgs, 0, X); PyTuple_SetItem(pArgs, 1, Y); pValue = PyEval_CallObject(pFunc, pArgs); res = PyFloat_AsDouble(pValue); Py_DECREF(X); Py_DECREF(Y); Py_DECREF(pArgs); return res; } How about the IronPython/C# or even F#? How to call the C#/F# function from IronPython? Or, is there any SWIG equivalent tool in IronPython/C#? How to call the IronPython function from C#/F#? I guess I could use "engine.CreateScriptSourceFromString" or similar, but I need to find a way to call IronPython function look like a C#/F# function.

    Read the article

  • How to treat Base* pointer as Derived<T>* pointer?

    - by dehmann
    I would like to store pointers to a Base class in a vector, but then use them as function arguments where they act as a specific class, see here: #include <iostream> #include <vector> class Base {}; template<class T> class Derived : public Base {}; void Foo(Derived<int>* d) { std::cerr << "Processing int" << std::endl; } void Foo(Derived<double>* d) { std::cerr << "Processing double" << std::endl; } int main() { std::vector<Base*> vec; vec.push_back(new Derived<int>()); vec.push_back(new Derived<double>()); Foo(vec[0]); Foo(vec[1]); delete vec[0]; delete vec[1]; return 0; } This doesn't compile: error: call of overloaded 'Foo(Base*&)' is ambiguous Is it possible to make it work? I need to process the elements of the vector differently, according to their int, double, etc. types.

    Read the article

  • Apache Lucene: Is Relevance Score Always Between 0 and 1?

    - by Eamorr
    Greetings, I have the following Apache Lucene snippet that's giving me some nice results: int numHits=100; int resultsPerPage=100; IndexSearcher searcher=new IndexSearcher(reader); TopScoreDocCollector collector=TopScoreDocCollector.create(numHits,true); Query q=parser.parse(queryString); searcher.search(q,collector); ScoreDoc[] hits=collector.topDocs(0*resultsPerPage,resultsPerPage).scoreDocs; Results r=new Results(); r.length=hits.length; for(int i=0;i<hits.length;i++){ Document doc=searcher.doc(hits[i].doc); double distanceKm=getGreatCircleDistance(lucene2double(doc.get("lat")), lucene2double(doc.get("lng")), Double.parseDouble(userLat), Double.parseDouble(userLng)); double newRelevance=((1/distanceKm)*Math.log(hits[i].score)/Math.log(2))*(0-1); System.out.println(hits[i].doc+"\t"+hits[i].score+"\t"+doc.get("content")+"\t"+"Km="+distanceKm+"\trlvnc="+String.valueOf(newRelevance)); } What I want to know, is hits[i].score always between 0 and 1? It seems that way, but I can't be sure. I've even checked the Lucene documentation (class ScoreDocs) to no avail. You'll see I'm calculating the log of the "newRelevance" value, which is based on hits[i].score. I need hits[i].score to be between 0 and 1, because if it is below zero, I'll get an error; above 1 and the sign will change from negative to positive. I hope some Lucene expert out there can offer me some insight. Many thanks,

    Read the article

< Previous Page | 53 54 55 56 57 58 59 60 61 62 63 64  | Next Page >