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• Getting PCM values of WAV files

  - by user2431088

  I have a .wav mono file (16bit,44.1kHz) and im using this code below. If im not wrong, this would give me an output of values between -1 and 1 which i can apply FFT on ( to be converted to a spectrogram later on). However, my output is no where near -1 and 1. This is a portion of my output 7.01214599609375 17750.2552337646 8308.42733764648 0.000274658203125 1.00001525878906 0.67291259765625 1.3458251953125 16.0000305175781 24932 758.380676269531 0.0001068115234375 This is the code which i got from another post Edit 1: public static Double[] prepare(String wavePath, out int SampleRate) { Double[] data; byte[] wave; byte[] sR = new byte[4]; System.IO.FileStream WaveFile = System.IO.File.OpenRead(wavePath); wave = new byte[WaveFile.Length]; data = new Double[(wave.Length - 44) / 4];//shifting the headers out of the PCM data; WaveFile.Read(wave, 0, Convert.ToInt32(WaveFile.Length));//read the wave file into the wave variable /***********Converting and PCM accounting***************/ for (int i = 0; i < data.Length; i += 2) { data[i] = BitConverter.ToInt16(wave, i) / 32768.0; } /**************assigning sample rate**********************/ for (int i = 24; i < 28; i++) { sR[i - 24] = wave[i]; } SampleRate = BitConverter.ToInt16(sR, 0); return data; }

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• Filling an Area in visual studio C#

  - by lajoo

  I'm drawing a circle in C# and i have divided it into some parts,i want to fill different parts with different colors,is there anyway to do this? and how?i tried using fillpie() but i couldn't get the arguments to work. here is the code: int r = 150; g.DrawEllipse(Pens.Black, 300 - r, 250 - r, 2 * r, 2 * r); if (p != 0) g.DrawLine(Pens.Black, 300, 250, 300 + r, 250); double sum; sum = 0.0; for (int j = 0; j < p; j++) sum += data[j].value; double angle; angle = 0.0; for (int i = 0; i < p; i++) { angle += (double)(data[i].value / sum) * 2.0 * Math.PI; textBox1.Text += sum.ToString() + " : " + angle.ToString() + ":" + Math.Cos(angle).ToString() + "\r\n"; g.DrawLine(Pens.Black, 300, 250, 300 + (int)(Math.Cos(angle) * r), 250 - (int)(Math.Sin(angle) * r)); //g.FillPie(Brushes.Black, 300-r , 250 - r, r, r ,(float)(angle),(float)(angle+ (data[i].value / sum) * 2.0 * Math.PI)); } this actually divides the circle into different parts,i don't know how to fill them the commented line is where i

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• Varying performance of MSVC release exe

  - by Andrew

  Hello everyone, I am curious what could be the reason for highly varying performance of the same executable. Sometimes, I run it and it takes 20 seconds and sometimes it is 110. Source is compiled with MSVC in Release mode with standard options. The code is here: vector<double> Un; vector<double> Ucur; double *pUn, *pUcur; ... // time marching for (old_time=time-logfreq, time+=dt; time <= end_time; time+=dt) { for (i=1, j=Un.size()-1, pUn=&Un[1], pUcur=&Ucur[1]; i < j; ++i, ++pUn, ++pUcur) { *pUcur = (*pUn)*(1.0-0.5*alpha*( *(pUn+1) - *(pUn-1) )); } Ucur[0] = (Un[0])*(1.0-0.5*alpha*( Un[1] - Un[j] )); Ucur[j] = (Un[j])*(1.0-0.5*alpha*( Un[0] - Un[j-1] )); Un = Ucur; }

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• Deserialize complex JSON (VB.NET)

  - by Ssstefan

  I'm trying to deserialize json returned by some directions API similar to Google Maps API. My JSON is as follows (I'm using VB.NET 2008): jsontext = { "version":0.3, "status":0, "route_summary": { "total_distance":300, "total_time":14, "start_point":"43", "end_point":"42" }, "route_geometry":[[51.025421,18.647631],[51.026131,18.6471],[51.027802,18.645639]], "route_instructions": [["Head northwest on 43",88,0,4,"88 m","NW",334.8],["Continue on 42",212,1,10,"0.2 km","NW",331.1,"C",356.3]] } So far I came up with the following code: Dim js As New System.Web.Script.Serialization.JavaScriptSerializer Dim lstTextAreas As Output_CloudMade() = js.Deserialize(Of Output_CloudMade())(jsontext) I'm not sure how to define complex class, i.e. Output_CloudMade. I'm trying something like: Public Class RouteSummary Private mTotalDist As Long Private mTotalTime As Long Private mStartPoint As String Private mEndPoint As String Public Property TotalDist() As Long Get Return mTotalDist End Get Set(ByVal value As Long) mTotalDist = value End Set End Property Public Property TotalTime() As Long Get Return mTotalTime End Get Set(ByVal value As Long) mTotalTime = value End Set End Property Public Property StartPoint() As String Get Return mStartPoint End Get Set(ByVal value As String) mStartPoint = value End Set End Property Public Property EndPoint() As String Get Return mEndPoint End Get Set(ByVal value As String) mEndPoint = value End Set End Property End Class Public Class Output_CloudMade Private mVersion As Double Private mStatus As Long Private mRSummary As RouteSummary 'Private mRGeometry As RouteGeometry 'Private mRInstructions As RouteInstructions Public Property Version() As Double Get Return mVersion End Get Set(ByVal value As Double) mVersion = value End Set End Property Public Property Status() As Long Get Return mStatus End Get Set(ByVal value As Long) mStatus = value End Set End Property Public Property Summary() As RouteSummary Get Return mRSummary End Get Set(ByVal value As RouteSummary) mRSummary = value End Set End Property 'Public Property Geometry() As String ' Get ' End Get ' Set(ByVal value As String) ' End Set 'End Property 'Public Property Instructions() As String ' Get ' End Get ' Set(ByVal value As String) ' End Set 'End Property End Class but it does not work. The problem is with complex properties, like route_summary. It is filled with "nothing". Other properties, like "status" or "version" are filled properly. Any ideas, how to define class for the above JSON? Can you share some working code for deserializing JSON in VB.NET? Thanks,

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• C# COM Cross Thread problem

  - by user364676

  Hi, we're developing a software to control a scientific measuring device. it provides a COM-Interface defines serveral functions to set measurement parameters and fires an event when it measured data. in order to test our software, i'm implementing a simulation of that device. the com-object runs a loop which periodically fires the event. another loop in the client app should now setup up the com-simulator using the given functions. i created a class for measuring parameters which will be instanciated when setting up a new measurement. // COM-Object public class MeasurementParams { public double Param1; public double Param2; } public class COM_Sim : ICOMDevice { public MeasurementParams newMeasurement; IClient client; public int NewMeasurement() { newMeasurment = new MeasurementParam(); } public int SetParam1(double val) { // why is newMeasurement null when method is called from client loop newMeasurement.Param1 = val; } void loop() { while(true) { // fire event client.HandleEvent; } } } public class Client : IClient { ICOMDevice server; public int HandleEvent() { // handle this event server.NewMeasurement(); server.SetParam1(0.0); } void loop() { while(true) { // do some stuff... server.NewMeasurement(); server.SetParam1(0.0); } } } both of the loops run in independent threads. when server.NewMeasurement() is called, the object on the server is set to a new instance. but in the next function, the object is null again. do the same when handling the server-event, it works perfectly, because the method runs in the servers thread. how to make it work from client-thread as well. as the client is meant to be working with the real device, i cannot modify the interfaces given by the manufactor. also i need to setup measurements independent from the event-handler, which will be fired not regulary. i assume this problem related to multithreaded-COM behavior but i found nothing on this topic.

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• java - codesprint2 programming contest answer

  - by arya

  I recently took part in Codesprint2. I was unable to submit the solution to the following question. http://www.spoj.pl/problems/COINTOSS/ ( I have posted the link to the problem statement at spoj because the codesprint link requires login ) I checked out one of the successful solutions, ( url : http://pastebin.com/uQhNh9Rc ) and the logic used is exactly the same as mine, yet I am still getting "Wrong Answer" I would be very thankful if someone could please tell me what error I have made, as I am unable to find it. Thank you. My code : import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.text.DecimalFormat; import java.util.StringTokenizer; public class Solution { static double solve( int n, int m ) { if( m==n ) return 0; if( m==0 ) return ( Math.pow( 2, n+1 ) - 2 ); else { double res = 1 + ( Double )( solve( n, m+1 ) + solve( n, 0 ))/2; return res; } } public static void main( String[] args ) throws IOException { BufferedReader br = new BufferedReader( new InputStreamReader( System.in )); int n, m; int t = Integer.parseInt( br.readLine() ); StringTokenizer tok; String s; for( int T=0; T<t; T++ ) { s = br.readLine(); tok = new StringTokenizer( s ); n = Integer.parseInt( tok.nextToken() ); m = Integer.parseInt( tok.nextToken() ); DecimalFormat df = new DecimalFormat(); df.setMaximumFractionDigits(2); df.setMinimumFractionDigits(2); System.out.println( df.format ( solve( n, m ) )); } } }

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• C# vs C - Big performance difference

  - by John

  I'm finding massive performance differences between similar code in C anc C#. The C code is: #include <stdio.h> #include <time.h> #include <math.h> main() { int i; double root; clock_t start = clock(); for (i = 0 ; i <= 100000000; i++){ root = sqrt(i); } printf("Time elapsed: %f\n", ((double)clock() - start) / CLOCKS_PER_SEC); } And the C# (console app) is: using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { DateTime startTime = DateTime.Now; double root; for (int i = 0; i <= 100000000; i++) { root = Math.Sqrt(i); } TimeSpan runTime = DateTime.Now - startTime; Console.WriteLine("Time elapsed: " + Convert.ToString(runTime.TotalMilliseconds/1000)); } } } With the above code, the C# completes in 0.328125 seconds (release version) and the C takes 11.14 seconds to run. The c is being compiled to a windows executable using mingw. I've always been under the assumption that C/C++ were faster or at least comparable to C#.net. What exactly is causing the C to run over 30 times slower? EDIT: It does appear that the C# optimizer was removing the root as it wasn't being used. I changed the root assignment to root += and printed out the total at the end. I've also compiled the C using cl.exe with the /O2 flag set for max speed. The results are now: 3.75 seconds for the C 2.61 seconds for the C# The C is still taking longer, but this is acceptable

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• Problem with std::ostringstream

  - by Dony

  Hi, I tried to make the code #1 more terse by changing it to code #2 but it doesn't work as expected. Can anyone please tell me why it doesn't work? Thanks. Code #1 double x = 8.9, y = 3.4, z = -4.5; std::ostringstream q0; q0 << "(" << x << "," << y << "," << z << ")"; std::string s = q0.str(); Code #2 double x = 8.9, y = 3.4, z = -4.5; std::string s = static_cast<std::ostringstream &>( std::ostringstream() << "(" << x << "," << y << "," << z << ")").str(); EDIT : Even code #3 works. Then why does code #2 not? Code #3 double x = 8.9, y = 3.4, z = -4.5; std::string s = static_cast<std::ostringstream *>( &(std::ostringstream() << "(" << x << "," << y << "," << z << ")"))->str();

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• MEF GetExports<T, TMetaDataView> returning nothing with AllowMultiple = True

  - by sohum

  I don't understand MEF very well, so hopefully this is a simple fix of how I think it works. I'm trying to use MEF to get some information about a class and how it should be used. I'm using the Metadata options to try to achieve this. My interfaces and attribute looks like this: public interface IMyInterface { } public interface IMyInterfaceInfo { Type SomeProperty1 { get; } double SomeProperty2 { get; } string SomeProperty3 { get; } } [MetadataAttribute] [AttributeUsage(AttributeTargets.Class, AllowMultiple = true)] public class ExportMyInterfaceAttribute : ExportAttribute, IMyInterfaceInfo { public ExportMyInterfaceAttribute(Type someProperty1, double someProperty2, string someProperty3) : base(typeof(IMyInterface)) { SomeProperty1 = someProperty1; SomeProperty2 = someProperty2; SomeProperty3 = someProperty3; } public Type SomeProperty1 { get; set; } public double SomeProperty2 { get; set; } public string SomeProperty3 { get; set; } } The class that is decorated with the attribute looks like this: [ExportMyInterface(typeof(string), 0.1, "whoo data!")] [ExportMyInterface(typeof(int), 0.4, "asdfasdf!!")] public class DecoratedClass : IMyInterface { } The method that is trying to use the import looks like this: private void SomeFunction() { // CompositionContainer is an instance of CompositionContainer var myExports = CompositionContainer.GetExports<IMyInterface, IMyInterfaceInfo>(); } In my case myExports is always empty. In my CompositionContainer, I have a Part in my catalog that has two ExportDefinitions, both with the following ContractName: "MyNamespace.IMyInterface". The Metadata is also loaded correctly per my exports. If I remove the AllowMultiple setter and only include one exported attribute, the myExports variable now has the single export with its loaded metadata. What am I doing wrong?

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• Inner angle between two lines

  - by ocell

  Hi folks, I have two lines: Line1 and Line2. Each line is defined by two points (P1L1(x1, y1), P2L1(x2, y2) and P1L1(x1, y1), P2L3(x2, y3)). I want to know the inner angle defined by these two lines. For do it I calculate the angle of each line with the abscissa: double theta1 = atan(m1) * (180.0 / PI); double theta2 = atan(m2) * (180.0 / PI); After to know the angle I calculate the following: double angle = abs(theta2 - theta1); The problem or doubt that I have is: sometimes I get the correct angle but sometimes I get the complementary angle (for me outer). How can I know when subtract 180º to know the inner angle? There is any algorithm better to do that? Because I tried some methods: dot product, following formula: result = (m1 - m2) / (1.0 + (m1 * m2)); But always I have the same problem; I never known when I have the outer angle or the inner angle! Thanks in advance for reading my trouble and for your time! Oscar.

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• Escaping colons in hibernate createSQLQuery

  - by Stratosgear

  I am confused on how I can create an SQL statement containing colons. I am trying to create a view and I am using (notice the double colons): create view MyView as ( SELECT tableA.colA as colA, tableB.colB as colB, round(tableB.colD / 1024)::numeric, 2) as calcValue, FROM tableA, tableB WHERE tableA.colC = 'someValue' ); This is a postgres query and I am forced to use the double colons (::) in order to correctly run the statement. I then pass the above statement through: s.createSQLQuery(myQuery).executeUpdate(); and I get a: Exception in thread "main" org.hibernate.exception.DataException: \ could not execute native bulk manipulation query at org.hibernate.exception.SQLStateConverter.convert(\ SQLStateConverter.java:102) ... more stacktrace... with an output of my above statement changed as (notice the question mark): create view MyView as ( SELECT tableA.colA as colA, tableB.colB as colB, round(tableB.colD / 1024)?, 2) as calcValue, FROM tableA, tableB WHERE tableA.colC = 'someValue' ); Obviously, hibernate confuses my colons with named parameters. Is there a way to escape the colons (a google suggestion that mentions that a single colon is escaped as a double colon does NOT work) or another way of running this statement? Thanks.

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• Pear HTML BBcode Hyperlink

  - by rrrfusco

  Has anyone used the PEAR HTML BBcode Package? I don't really understand why hyperlink target _blank does not open a new tab in firefox. INSERT Snippet [url=http://site.com t=_blank]Link[/url] PHP Require PEAR require_once 'HTML/BBCodeParser.php'; $options = @parse_ini_file('BBCodeParser.ini'); $parser = new HTML_BBCodeParser($options); $parser->setText($text); $parser->parse(); echo $parser->getParsed(); BBCodeParser.ini [HTML_BBCodeParser] ; http://articles.sitepoint.com/article/bb-code-php-application/ ; possible values: single|double ; use single or double quotes for attributes quotestyle = double ; possible values: all|nothing|strings ; quote all attribute values, none, or only the strings quotewhat = all ; the opening tag character open = "[" ; the closing tag character close = "]" ; possible values: true|false ; use xml style closing tags for single html tags (<img> or <img />) xmlclose = true ; possible values: a comma seperated list of filters ; comma seperated list of filters to use filters = Basic,Extended,Links,Images,Lists ; filters = Basic,Extended,Links,Images,Lists,Email,MyBB

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• Dynamic memory inside a struct

  - by Maximilien

  Hello, I'm editing a piece of code, that is part of a big project, that uses "const's" to initialize a bunch of arrays. Because I want to parametrize these const's I have to adapt the code to use "malloc" in order to allocate the memory. Unfortunately there is a problem with structs: I'm not able to allocate dynamic memory in the struct itself. Doing it outside would cause to much modification of the original code. Here's a small example: int globalx,globaly; struct bigStruct{ struct subStruct{ double info1; double info2; bool valid; }; double data; //subStruct bar[globalx][globaly]; subStruct ** bar=(subStruct**)malloc(globalx*sizeof(subStruct*)); for(int i=0;i<globalx;i++) bar[i]=(*subStruct)malloc(globaly*sizeof(subStruct)); }; int main(){ globalx=2; globaly=3; bigStruct foo; for(int i=0;i<globalx;i++) for(int j=0;j<globaly;j++){ foo.bar[i][j].info1=i+j; foo.bar[i][j].info2=i*j; foo.bar[i][j].valid=(i==j); } return 0; } Note: in the program code I'm editing globalx and globaly were const's in a specified namespace. Now I removed the "const" so they can act as parameters that are set exactly once. Summarized: How can I properly allocate memory for the substruct inside the struct? Thank you very much! Max

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• Converting currencies via intermediate currencies.

  - by chillitom

  class FxRate { string Base { get; set; } string Target { get; set; } double Rate { get; set; } } private IList<FxRate> rates = new List<FxRate> { new FxRate {Base = "EUR", Target = "USD", Rate = 1.3668}, new FxRate {Base = "GBP", Target = "USD", Rate = 1.5039}, new FxRate {Base = "USD", Target = "CHF", Rate = 1.0694}, new FxRate {Base = "CHF", Target = "SEK", Rate = 8.12} // ... }; Given a large yet incomplete list of exchange rates where all currencies appear at least once (either as a target or base currency): What algorithm would I use to be able to derive rates for exchanges that aren't directly listed? I'm looking for a general purpose algorithm of the form: public double Rate(string baseCode, string targetCode, double currency) { return ... } In the example above a derived rate would be GBP-CHF or EUR-SEK (which would require using the conversions for EUR-USD, USD-CHF, CHF-SEK) Whilst I know how to do the conversions by hand I'm looking for a tidy way (perhaps using LINQ) to perform these derived conversions perhaps involving multiple currency hops, what's the nicest way to go about this?

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• accumulator don't compile

  - by Abruzzo Forte e Gentile

  HI All I am using boost accumulators. These 2 lines use to work fine with current version of boost in LInux. accumulator_set< double, stats< tag::covariance<double, tag::covariate1> > > acc_cov; accumulator_set< double, stats< tag::variance > > acc_var; When I moved to a Sun machine where it is installed boost v1.40 I have this building error "/opt/boost/boost/accumulators/framework/depends_on.hpp", line 276: Error:<no tag> cannot be initialized in a constructor. "/opt/boost/boost/fusion/container/list/cons.hpp", line 85: Where: While instantiating "boost::accumulators::detail::accumulator_wrapper<int, int>::accumulator_wrapper(const boost::accumulators::detail::accumulator_wrapper<int, int>&)". "/opt/boost/boost/fusion/container/list/cons.hpp", line 85: Where: Instantiated from non-template code. 1 Error(s) Do you know how can I fix those errors and why I have this issue? Thanks AFG

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• Best way to get a single value from a DataTable?

  - by PiersMyers

  I have a number of static classes that contain tables like this: using System; using System.Data; using System.Globalization; public static class TableFoo { private static readonly DataTable ItemTable; static TableFoo() { ItemTable = new DataTable("TableFoo") { Locale = CultureInfo.InvariantCulture }; ItemTable.Columns.Add("Id", typeof(int)); ItemTable.Columns["Id"].Unique = true; ItemTable.Columns.Add("Description", typeof(string)); ItemTable.Columns.Add("Data1", typeof(int)); ItemTable.Columns.Add("Data2", typeof(double)); ItemTable.Rows.Add(0, "Item 1", 1, 1.0); ItemTable.Rows.Add(1, "Item 2", 1, 1.0); ItemTable.Rows.Add(2, "Item 3", 2, 0.75); ItemTable.Rows.Add(3, "Item 4", 4, 0.25); ItemTable.Rows.Add(4, "Item 5", 1, 1.0); } public static DataTable GetItemTable() { return ItemTable; } public static int Data1(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (int)dr[0]["Data1"]; } public static double Data2(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (double)dr[0]["Data2"]; } } Is there a better way of writing the Data1 or Data2 methods that return a single value from a single row that matches the given id?

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• Stored procedure using cursor in mySql.

  - by RAVI

  I wrote a stored procedure using cursor in mysql but that procedure is taking 10 second to fetch the result while that result set have only 450 records so, I want to know that why that proedure is taking that much time to fetch tha record. procedure as below: DELIMITER // DROP PROCEDURE IF EXISTS curdemo123// CREATE PROCEDURE curdemo123(IN Branchcode int,IN vYear int,IN vMonth int) BEGIN DECLARE EndOfData,tempamount INT DEFAULT 0; DECLARE tempagent_code,tempplantype,tempsaledate CHAR(12); DECLARE tempspot_rate DOUBLE; DECLARE var1,totalrow INT DEFAULT 1; DECLARE cur1 CURSOR FOR select SQL_CALC_FOUND_ROWS ad.agentCode,ad.planType,ad.amount,ad.date from adplan_detailstbl ad where ad.branchCode=Branchcode and (ad.date between '2009-12-1' and '2009-12-31')order by ad.NUM_ID asc; DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET EndOfData = 1; DROP TEMPORARY TABLE IF EXISTS temptable; CREATE TEMPORARY TABLE temptable (agent_code varchar(15), plan_type char(12),sale double,spot_rate double default '0.0', dATE DATE); OPEN cur1; SET totalrow=FOUND_ROWS(); while var1 <= totalrow DO fetch cur1 into tempagent_code,tempplantype,tempamount,tempsaledate; IF((tempplantype='Unit Plan' OR tempplantype='MIP') OR tempplantype='STUP') then select spotRate into tempspot_rate from spot_amount where ((monthCode=vMonth and year=vYear) and ((agentCode=tempagent_code and branchCode=Branchcode) and (planType=tempplantype))); INSERT INTO temptable VALUES(tempagent_code,tempplantype,tempamount,tempspot_rate,tempsaledate); else INSERT INTO temptable(agent_code,plan_type,sale,dATE) VALUES(tempagent_code,tempplantype,tempamount,tempsaledate); END IF; SET var1=var1+1; END WHILE; CLOSE cur1; select * from temptable; DROP TABLE temptable; END // DELIMITER ;

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• RBG to CbyCr conversion code

  - by user1446688

  I am wondering why this code does not work. Basically it is supposed to convert between RGB and CbYCr. When I convert from RGB to CbYCr then back to RGB I do not get the original RGB values. What is wrong with this code? #define MIN(a,b) (((a)<(b))?(a):(b)) #define MAX(a,b) (((a)(b))?(a):(b)) struct _rgb { int R; int G; int B; }; typedef struct _rgb rgb; struct _cbycr { int Cb; int Y; int Cr; }; typedef struct _cbycr cbycr; void cbycr2rgb(rgb *c, double Y, double Cb, double Cr) { int r = (int)(Y + 1.40200 * (Cr - 0x80)); int g = (int)(Y - 0.34414 * (Cb - 0x80) - 0.71414 * (Cr - 0x80)); int b = (int)(Y + 1.77200 * (Cb - 0x80)); c->R = MAX(0, MIN(255, r)); c->G = MAX(0, MIN(255, g)); c->B = MAX(0, MIN(255, b)); } void rgb2cbycr(cbycr *c, int R, int G, int B) { c->Y = (int)(0.299 * R + 0.587 * G + 0.114 * B); c->Cb = (int)(-0.16874 * R - 0.33126 * G + 0.50000 * B); c->Cr =(int)(0.50000 * R - 0.41869 * G - 0.08131 * B); } int main() { cbycr _cbycr; rgb _rgb; _rgb.R = 50; _rgb.G = 50; _rgb.B = 50; rgb2cbycr(&_cbycr, _rgb.R, _rgb.G, _rgb.B); cbycr2rgb(&_rgb, _cbycr.Y, _cbycr.Cb, _cbycr.Cr); printf("rgb=%d %d %d\n", _rgb.R, _rgb.G, _rgb.B); return 0; } output: rgb=0 185 0

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• Intellisense on custom types in Iron Python

  - by Anish Patel

  Hi everybody, I'm just starting to play around with IronPython and am having a hard time using it with custom types created in C#. I can get IronPython to load in assemblies from C# classes, but I'm struggling without the help of intellisense. If I have a class in C# as defined below, how can I make it so that IronPython will be able to see the methods/properties that are available in it? public class Person { public string Name { get; set; } public int Age{ get; set; } public double Weight{ get; set; } public double Height { get; set; } public double CalculateBMI() { return Weight/Math.Pow(Height, 2); } } In Iron python I'd instance a Person object as follows: newPerson = Person() newPerson.Name = 'John' newPerson.Age = 25 newPerson.Weight = 75 newPerson.Height = 1.70 newPerson.CalculateBMI() The thing that is annoying me is that I want to be able to say newPerson = Person() And then be able to see all the methods and properties associated with the person object whenever I type: newPerson. Anyone have any ideas if this can be done?

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• Suppressing PostSharp Multicast with Attribute

  - by Dan Bryant

  I've recently started experimenting with PostSharp and I found a particularly helpful aspect to automate implementation of INotifyPropertyChanged. You can see the example here. The basic functionality is excellent (all properties will be notified), but there are cases where I might want to suppress notification. For instance, I might know that a particular property is set once in the constructor and will never change again. As such, there is no need to emit the code for NotifyPropertyChanged. The overhead is minimal when classes are not frequently instantiated and I can prevent the problem by switching from an automatically generated property to a field-backed property and writing to the field. However, as I'm learning this new tool, it would be helpful to know if there is a way to tag a property with an attribute to suppress the code generation. I'd like to be able to do something like this: [NotifyPropertyChanged] public class MyClass { public double SomeValue { get; set; } public double ModifiedValue { get; private set; } [SuppressNotify] public double OnlySetOnce { get; private set; } public MyClass() { OnlySetOnce = 1.0; } }

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• How do I update a progress bar in Cocoa during a long running loop?

  - by Nic

  Hi, I've got a while loop, that runs for many seconds and that's why I want to update a progress bar (NSProgressIndicator) during that process, but it updates only once after the loop has finished. The same happens if I want to update a label text, by the way. I believe, my loop prevents other things of that application to happen. There must be another technique. Does this have to do with threads or something? Am I on the right track? Can someone please give me a simple example, how to “optimize” my application? My application is a Cocoa Application (Xcode 3.2.1) with these two methods in my Example_AppDelegate.m: // This method runs when a start button is clicked. - (IBAction)startIt:(id)sender { [progressbar setDoubleValue:0.0]; [progressbar startAnimation:sender]; running = YES; // this is a instance variable int i = 0; while (running) { if (i++ = processAmount) { // processAmount is something like 1000000 running = NO; continue; } // Update progress bar double progr = (double)i / (double)processAmount; NSLog(@"progr: %f", progr); // Logs values between 0.0 and 1.0 [progressbar setDoubleValue:progr]; [progressbar needsDisplay]; // Do I need this? // Do some more hard work here... } } // This method runs when a stop button is clicked, but as long // as -startIt is busy, a click on the stop button does nothing. - (IBAction)stopIt:(id)sender { NSLog(@"Stop it!"); running = NO; [progressbar stopAnimation:sender]; } I'm really new to Objective-C, Cocoa and applications with a UI. Thank you very much for any helpful answer.

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• How best to calculate derived currency rate conversions using C#/LINQ?

  - by chillitom

  class FxRate { string Base { get; set; } string Target { get; set; } double Rate { get; set; } } private IList<FxRate> rates = new List<FxRate> { new FxRate {Base = "EUR", Target = "USD", Rate = 1.3668}, new FxRate {Base = "GBP", Target = "USD", Rate = 1.5039}, new FxRate {Base = "USD", Target = "CHF", Rate = 1.0694}, new FxRate {Base = "CHF", Target = "SEK", Rate = 8.12} // ... }; Given a large yet incomplete list of exchange rates where all currencies appear at least once (either as a target or base currency): What algorithm would I use to be able to derive rates for exchanges that aren't directly listed? I'm looking for a general purpose algorithm of the form: public double Rate(string baseCode, string targetCode, double currency) { return ... } In the example above a derived rate would be GBP-CHF or EUR-SEK (which would require using the conversions for EUR-USD, USD-CHF, CHF-SEK) Whilst I know how to do the conversions by hand I'm looking for a tidy way (perhaps using LINQ) to perform these derived conversions perhaps involving multiple currency hops, what's the nicest way to go about this?

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• Some optimization about the code (computing ranks of a vector)?

  - by user1748356

  The following code is a function (performance-critical) to compute tied ranks of a vector: mergeSort(x,inds,ci); //a sort function to sort vector x of length ci, also returns keys (inds) of x. int tj=0; double xi=x[0]; for (int j = 1; j < ci; ++j) { if (x[j] > xi) { double rankvalue = 0.5 * (j - 1 + tj); for (int k = tj; k < j; ++k) { ranks[inds[k]]=rankvalue; }; tj = j; xi = x[j]; }; }; double rankvalue = 0.5 * (ci - 1 + tj); for (int k = tj; k < ci; ++k) { ranks[inds[k]]=rankvalue; }; The problem is, the supposed performance bottleneck mergeSort(), which is O(NlogN) is several times faster than the other part of codes (which is O(N)), which suggests there is room for huge improvment with the other part of the codes, any advices?

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• How do I create a graph from this datastructure?

  - by Shawn Mclean

  I took this data structure from this A* tutorial: public interface IHasNeighbours<N> { IEnumerable<N> Neighbours { get; } } public class Path<TNode> : IEnumerable<TNode> { public TNode LastStep { get; private set; } public Path<TNode> PreviousSteps { get; private set; } public double TotalCost { get; private set; } private Path(TNode lastStep, Path<TNode> previousSteps, double totalCost) { LastStep = lastStep; PreviousSteps = previousSteps; TotalCost = totalCost; } public Path(TNode start) : this(start, null, 0) { } public Path<TNode> AddStep(TNode step, double stepCost) { return new Path<TNode>(step, this, TotalCost + stepCost); } public IEnumerator<TNode> GetEnumerator() { for (Path<TNode> p = this; p != null; p = p.PreviousSteps) yield return p.LastStep; } IEnumerator IEnumerable.GetEnumerator() { return this.GetEnumerator(); } } I have no idea how to create a simple graph with. How do I add something like the following undirected graph using C#: Basically I'd like to know how to connect nodes. I have my own datastructures that I can already determine the neighbors and the distance. I'd now like to convert that into this posted datastructure so I can run it through the AStar algorithm. I was seeking something more like: Path<EdgeNode> startGraphNode = new Path<EdgeNode>(tempStartNode); startGraphNode.AddNeighbor(someOtherNode, distance);

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• c# syntax and Linq, IQueryable

  - by hdiver

  Hello. This is a question about the SYNTAX of c# and NOT about how we call/use IQueryable Can someone please explain to me: We have this declaration (System.Linq): public static double Average<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, int>> selector) and to call the Average double average = fruits.AsQueryable().Average(s => s.Length); I understand how to call the Average and all the similar static method of IQueryable but I don’t understand the syntax of the declaration. public static double Average<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, int>> selector) What does the <TSource> mean in Average<TSource>( and also the this IQueryable<TSource> source. since only one parameter passes when we call it and the actual lamda expression (s => s.Length); Thanks in advance.

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