Search Results

Search found 18028 results on 722 pages for 'atomic values'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 85/722 | < Previous Page | 81 82 83 84 85 86 87 88 89 90 91 92  | Next Page >

  • What is the standard way of using Q15 values?

    - by Alex
    To process 8-bit pixels, to do things like gamma correction without losing information, we normally upsample the values, work in 16 bits or whatever, and then downsample them to 8 bits. Now, this is a somewhat new area for me, so please excuse incorrect terminology etc. For my needs I have chosen to work in "non-standard" Q15, where I only use the upper half of the range (0.0-1.0), and 0x8000 represents 1.0 instead of -1.0. This makes it much easier to calculate things in C. But I ran into a problem with SSSE3. It has the PMULHRSW instruction which multiplies Q15 numbers, but it uses the "standard" range of Q15 is [-1,1-2?¹5], so multplying (my) 0x8000 (1.0) by 0x4000 (0.5) gives 0xC000 (-0.5), because it thinks 0x8000 is -1. This is quite annoying. What am I doing wrong? Should I keep my pixel values in the 0000-7FFF range? This kind of defeats the purpose of it being a fixed-point format. Is there a way around this? Maybe some trick? Is there some kind of definitive treatise on Q15 which discusses all this?

    Read the article

  • How to replace values in multi-valued ESE column?

    - by Soonts
    I have a multi-valued short ASCII text column in one of the tables in my ESE database, that holds the person's phone numbers. I have the new set of values, and I'd like to wipe the old values completely, and only use the new values. The JET_bitSetRevertToDefaultValue bit doesn't seem to work. While the MSDN documentation says "It causes the column to return the default column value on subsequent retrieve column operations. All existing column values are removed.", I found that it does nothing (no return value is returned). Or, is there an easy way to find out how many values does the column contain (this could be zero, e.g. when I'm doing an insertion, not update)? If it was, I could just run a loop from 'nValues' to 1, erasing the value by setting it to the null while providing the itagSequence value, to achieve what I want. I'm programming C#, and using the latest version of ManagedEsent library. Thanks in advance!

    Read the article

  • How can you pass GET values to another url in php? GET value forwarding

    - by gobackpacking
    Ok, so I'm using Jquery's AJAX function and it's having trouble passing a URL with a http address. So I'm hoping to "get" the GET values and send them to another URL — so: a local php file begin passed GET values, which in turn forwards the GET values to another url. Maybe curl is the answer? I don't know. It's got to be a very short answer I know. pseudo code: //retrieve the GET values $var retrieve [GET] //passing it to another url send get values to url ($var, url_address)

    Read the article

  • T SQL Rotate row into columns

    - by cshah
    SQL 2005 using T-SQL, I want to rotate rows into columns. Sample script: Use TempDB Go CREATE TABLE [dbo].[CPPrinter_InkLevels]( [CPPrinter_InkLevels_ID] [int] IDENTITY(1,1) NOT NULL, [CPMeasurementGUID] [uniqueidentifier] NOT NULL, [InkName] [varchar](30) NOT NULL, [InkLevel] [decimal](6, 2) NOT NULL, CONSTRAINT [PK_CPPrinter_InkLevels] PRIMARY KEY CLUSTERED ( [CPPrinter_InkLevels_ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET IDENTITY_INSERT [dbo].[CPPrinter_InkLevels] ON INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (1, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Black', CAST(0.60 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (2, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Cyan', CAST(0.69 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (3, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Magenta', CAST(0.55 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (4, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Yellow', CAST(0.51 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (5, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Light Black', CAST(0.64 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (6, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Light Cyan', CAST(0.43 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (7, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Light Magenta', CAST(0.30 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (8, N'6acc1562-4e02-45ff-b480-9e01fb97fccf', N'Waste Tank', CAST(0.18 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (9, N'932348a7-6e2f-4a10-9760-be1ae640c7d7', N'Black', CAST(0.60 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (10, N'932348a7-6e2f-4a10-9760-be1ae640c7d7', N'Cyan', CAST(0.69 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (11, N'932348a7-6e2f-4a10-9760-be1ae640c7d7', N'Magenta', CAST(0.55 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (12, N'932348a7-6e2f-4a10-9760-be1ae640c7d7', N'Yellow', CAST(0.51 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (13, N'932348a7-6e2f-4a10-9760-be1ae640c7d7', N'Light Black', CAST(0.64 AS Decimal(6, 2))) INSERT [dbo].[CPPrinter_InkLevels] ([CPPrinter_InkLevels_ID], [CPMeasurementGUID], [InkName], [InkLevel]) VALUES (14, N'932348a7-6e2f-4a10-9760-be1ae640c7d7', N'Light Cyan', CAST(0.43 AS Decimal(6, 2))) Go SELECT * FROM [dbo].[CPPrinter_InkLevels] --Desired output CPMeasuremnetGUID, Ink1, Level1, Ink2, Level2, Ink3, Level3....

    Read the article

  • How can/could/might you bind WPF DataGrid to a List of objects each with some values in a Dictionary

    - by panamack
    major edit of a tumbleweed, may remain a tumbleweed... If I have a list of Customers and the data for each Customer is contained in a Dictionary how can I bind the list to the DataGrid so that each string key is a column? Edit: N.B. I know it's not a nice way to design a Customer class. e.g. public class Customer{ public int Id{get;set;} private Dictionary<string,string> values; public Dictionary<string,string> Values{get {return values;}} public Customer(int id){ this.Id = id; values["Name"] = "Peter"; values["Age"] = 129.ToString(); values["HairColour"] = "See through!"; } } ... later that day... var Customers = new List<Customer>(){ new Customer(1), new Customer(2), new Customer(3) }; ... and then... <DataGrid ItemsSource={Binding Path=Customers}/> ... desired result. Id | Name | Age | HairColour ________________________ 1 | Peter| 129 | See through! ________________________ 2 | Peter| 129 | See through! ________________________ 3 | Peter| 129 | See through! ________________________

    Read the article

  • Setting Ringtone notification from SD card file

    - by sgarman
    My goal is to set the users notification sound from a file that is stored onto the SD card from with in the application. I am using this code: if(path != null){ File k = new File(path, "moment.mp3"); ContentValues values = new ContentValues(); values.put(MediaStore.MediaColumns.DATA, k.getAbsolutePath()); values.put(MediaStore.MediaColumns.TITLE, "My Song title"); values.put(MediaStore.MediaColumns.SIZE, 215454); values.put(MediaStore.MediaColumns.MIME_TYPE, "audio/mp3"); values.put(MediaStore.Audio.Media.ARTIST, "Some Artist"); values.put(MediaStore.Audio.Media.DURATION, 230); values.put(MediaStore.Audio.Media.IS_RINGTONE, false); values.put(MediaStore.Audio.Media.IS_NOTIFICATION, true); values.put(MediaStore.Audio.Media.IS_ALARM, false); values.put(MediaStore.Audio.Media.IS_MUSIC, false); values.put(MediaStore.MediaColumns.DISPLAY_NAME, "Some Name"); //Insert it into the database Uri uri = MediaStore.Audio.Media.getContentUriForPath(k.getAbsolutePath()); Uri newUri = MainActivity.this.getContentResolver().insert(uri, values); RingtoneManager.setActualDefaultRingtoneUri( MainActivity.this, RingtoneManager.TYPE_NOTIFICATION, newUri ); //RingtoneManager.setActualDefaultRingtoneUri(this, RingtoneManager.TYPE_NOTIFICATION, newUri); Toast.makeText(this, "Notification Ringtone Set", Toast.LENGTH_SHORT).show(); } When I run this on the device I keep getting the error: 06-12 15:19:36.741: ERROR/Database(2847): Error inserting is_alarm=false is_ringtone=false artist_id=35 is_music=false album_id=-1 title=My Song title duration=230 is_notification=true title_key=%D%\%%P%H%F%8%%R%<%R%B%4% mime_type=audio/mp3 date_added=1276370376 _display_name=moment.mp3 _size=215454 _data=/mnt/sdcard/Android/data/_MY APP PATH_/files/moment.mp3 06-12 15:19:36.741: ERROR/Database(2847): android.database.sqlite.SQLiteConstraintException: error code 19: constraint failed I have seen others using this technique and I can't find any documentation on which values actually need to be passed in to successfully add the file into the Android system so that it can be set as a notification.

    Read the article

  • Perl - CodeGolf - Nested loops & SQL inserts

    - by CheeseConQueso
    I had to make a really small and simple script that would fill a table with string values according to these criteria: 2 characters long 1st character is always numeric (0-9) 2nd character is (0-9) but also includes "X" Values need to be inserted into a table on a database The program would execute: insert into table (code) values ('01'); insert into table (code) values ('02'); insert into table (code) values ('03'); insert into table (code) values ('04'); insert into table (code) values ('05'); insert into table (code) values ('06'); insert into table (code) values ('07'); insert into table (code) values ('08'); insert into table (code) values ('09'); insert into table (code) values ('0X'); And so on, until the total 110 values were inserted. My code (just to accomplish it, not to minimize and make efficient) was: use strict; use DBI; my ($db1,$sql,$sth,%dbattr); %dbattr=(ChopBlanks => 1,RaiseError => 0); $db1=DBI->connect('DBI:mysql:','','',\%dbattr); my @code; for(0..9) { $code[0]=$_; for(0..9) { $code[1]=$_; insert(@code); } insert($code[0],"X"); } sub insert { my $skip=0; foreach(@_) { if($skip==0) { $sql="insert into table (code) values ('".$_[0].$_[1]."');"; $sth=$db1->prepare($sql); $sth->execute(); $skip++; } else { $skip--; } } } exit; I'm just interested to see a really succinct & precise version of this logic.

    Read the article

  • C#/.NET Little Wonders: Interlocked Read() and Exchange()

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Last time we discussed the Interlocked class and its Add(), Increment(), and Decrement() methods which are all useful for updating a value atomically by adding (or subtracting).  However, this begs the question of how do we set and read those values atomically as well? Read() – Read a value atomically Let’s begin by examining the following code: 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value { get { return _value; } } 6:  7: public void Increment() 8: { 9: Interlocked.Increment(ref _value); 10: } 11: } 12:  It uses an interlocked increment, as we discuss in my previous post (here), so we know that the increment will be thread-safe.  But, to realize what’s potentially wrong we have to know a bit about how atomic reads are in 32 bit and 64 bit .NET environments. When you are dealing with an item smaller or equal to the system word size (such as an int on a 32 bit system or a long on a 64 bit system) then the read is generally atomic, because it can grab all of the bits needed at once.  However, when dealing with something larger than the system word size (reading a long on a 32 bit system for example), it cannot grab the whole value at once, which can lead to some problems since this read isn’t atomic. For example, this means that on a 32 bit system we may read one half of the long before another thread increments the value, and the other half of it after the increment.  To protect us from reading an invalid value in this manner, we can do an Interlocked.Read() to force the read to be atomic (of course, you’d want to make sure any writes or increments are atomic also): 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value 6: { 7: get { return Interlocked.Read(ref _value); } 8: } 9:  10: public void Increment() 11: { 12: Interlocked.Increment(ref _value); 13: } 14: } Now we are guaranteed that we will read the 64 bit value atomically on a 32 bit system, thus ensuring our thread safety (assuming all other reads, writes, increments, etc. are likewise protected).  Note that as stated before, and according to the MSDN (here), it isn’t strictly necessary to use Interlocked.Read() for reading 64 bit values on 64 bit systems, but for those still working in 32 bit environments, it comes in handy when dealing with long atomically. Exchange() – Exchanges two values atomically Exchange() lets us store a new value in the given location (the ref parameter) and return the old value as a result. So just as Read() allows us to read atomically, one use of Exchange() is to write values atomically.  For example, if we wanted to add a Reset() method to our Incrementor, we could do something like this: 1: public void Reset() 2: { 3: _value = 0; 4: } But the assignment wouldn’t be atomic on 32 bit systems, since the word size is 32 bits and the variable is a long (64 bits).  Thus our assignment could have only set half the value when a threaded read or increment happens, which would put us in a bad state. So instead, we could write Reset() like this: 1: public void Reset() 2: { 3: Interlocked.Exchange(ref _value, 0); 4: } And we’d be safe again on a 32 bit system. But this isn’t the only reason Exchange() is valuable.  The key comes in realizing that Exchange() doesn’t just set a new value, it returns the old as well in an atomic step.  Hence the name “exchange”: you are swapping the value to set with the stored value. So why would we want to do this?  Well, anytime you want to set a value and take action based on the previous value.  An example of this might be a scheme where you have several tasks, and during every so often, each of the tasks may nominate themselves to do some administrative chore.  Perhaps you don’t want to make this thread dedicated for whatever reason, but want to be robust enough to let any of the threads that isn’t currently occupied nominate itself for the job.  An easy and lightweight way to do this would be to have a long representing whether someone has acquired the “election” or not.  So a 0 would indicate no one has been elected and 1 would indicate someone has been elected. We could then base our nomination strategy as follows: every so often, a thread will attempt an Interlocked.Exchange() on the long and with a value of 1.  The first thread to do so will set it to a 1 and return back the old value of 0.  We can use this to show that they were the first to nominate and be chosen are thus “in charge”.  Anyone who nominates after that will attempt the same Exchange() but will get back a value of 1, which indicates that someone already had set it to a 1 before them, thus they are not elected. Then, the only other step we need take is to remember to release the election flag once the elected thread accomplishes its task, which we’d do by setting the value back to 0.  In this way, the next thread to nominate with Exchange() will get back the 0 letting them know they are the new elected nominee. Such code might look like this: 1: public class Nominator 2: { 3: private long _nomination = 0; 4: public bool Elect() 5: { 6: return Interlocked.Exchange(ref _nomination, 1) == 0; 7: } 8: public bool Release() 9: { 10: return Interlocked.Exchange(ref _nomination, 0) == 1; 11: } 12: } There’s many ways to do this, of course, but you get the idea.  Running 5 threads doing some “sleep” work might look like this: 1: var nominator = new Nominator(); 2: var random = new Random(); 3: Parallel.For(0, 5, i => 4: { 5:  6: for (int j = 0; j < _iterations; ++j) 7: { 8: if (nominator.Elect()) 9: { 10: // elected 11: Console.WriteLine("Elected nominee " + i); 12: Thread.Sleep(random.Next(100, 5000)); 13: nominator.Release(); 14: } 15: else 16: { 17: // not elected 18: Console.WriteLine("Did not elect nominee " + i); 19: } 20: // sleep before check again 21: Thread.Sleep(1000); 22: } 23: }); And would spit out results like: 1: Elected nominee 0 2: Did not elect nominee 2 3: Did not elect nominee 1 4: Did not elect nominee 4 5: Did not elect nominee 3 6: Did not elect nominee 3 7: Did not elect nominee 1 8: Did not elect nominee 2 9: Did not elect nominee 4 10: Elected nominee 3 11: Did not elect nominee 2 12: Did not elect nominee 1 13: Did not elect nominee 4 14: Elected nominee 0 15: Did not elect nominee 2 16: Did not elect nominee 4 17: ... Another nice thing about the Interlocked.Exchange() is it can be used to thread-safely set pretty much anything 64 bits or less in size including references, pointers (in unsafe mode), floats, doubles, etc.  Summary So, now we’ve seen two more things we can do with Interlocked: reading and exchanging a value atomically.  Read() and Exchange() are especially valuable for reading/writing 64 bit values atomically in a 32 bit system.  Exchange() has value even beyond simply atomic writes by using the Exchange() to your advantage, since it reads and set the value atomically, which allows you to do lightweight nomination systems. There’s still a few more goodies in the Interlocked class which we’ll explore next time! Technorati Tags: C#,CSharp,.NET,Little Wonders,Interlocked

    Read the article

  • "Can't create table" when having to many partitions

    - by Chris
    I am currently having a problem I dont understand. Wherever I look it says mySQL (5.5) / InnoDB doesnt have a table limit. I wanted to test the InnoDB compression and was about to create an empty copy of an existing table and ran into the following problem. this one works: CREATE TABLE `hsc` ( LOTS OF STUFF ) ENGINE=InnoDB CHARSET=utf8 PARTITION BY RANGE (pid) SUBPARTITION BY HASH (cons) SUBPARTITIONS 2 (PARTITION hsc_p0 VALUES LESS THAN (10000) , PARTITION hsc_p1 VALUES LESS THAN (20000) , PARTITION hsc_p2 VALUES LESS THAN (30000) , PARTITION hsc_p3 VALUES LESS THAN (40000) , PARTITION hsc_p4 VALUES LESS THAN (50000) , PARTITION hsc_p40 VALUES LESS THAN (4000000) ); this one doesn't: CREATE TABLE `hsc` ( LOTS OF STUFF ) ENGINE=InnoDB CHARSET=utf8 PARTITION BY RANGE (pid) SUBPARTITION BY HASH (cons) SUBPARTITIONS 2 (PARTITION hsc_p0 VALUES LESS THAN (10000) , PARTITION hsc_p1 VALUES LESS THAN (20000) , PARTITION hsc_p2 VALUES LESS THAN (30000) , PARTITION hsc_p3 VALUES LESS THAN (40000) , PARTITION hsc_p4 VALUES LESS THAN (50000) , PARTITION hsc_p5 VALUES LESS THAN (75000) , PARTITION hsc_p6 VALUES LESS THAN (100000) , PARTITION hsc_p7 VALUES LESS THAN (125000) , PARTITION hsc_p8 VALUES LESS THAN (150000) , PARTITION hsc_p9 VALUES LESS THAN (175000) , PARTITION hsc_p40 VALUES LESS THAN (4000000) ); ERROR 1005 (HY000): Can't create table 'hsc' (errno: 1) Its reproducable by removing the number of partitions and adding them again. it does not have to do anything with the name of the table as i tried various names. there is also enough empty space on the HDD. /dev/simfs 230G 26G 192G 12% /var/lib/mysql.mnt There should be no limit on the partitions http://dev.mysql.com/doc/refman/5.5/en/partitioning-limitations.html Maximum number of partitions. The maximum possible number of partitions for a given table (that does not use the NDB storage engine) is 1024. This number includes subpartitions. i have increased both open_files show variables where variable_name LIKE '%open_files%'; +-------------------+-------+ | Variable_name | Value | +-------------------+-------+ | innodb_open_files | 512 | | open_files_limit | 1536 | +-------------------+-------+ No change. Any clues where should I start looking? UPDATE: the whole thing is running in an openvz environment. i saw in users_beancounters that the numflock was a problem, so i increased it. but the problem still persists. maybe this helps: ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 515011 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 10240 cpu time (seconds, -t) unlimited max user processes (-u) 515011 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited cat /proc/user_beancounters Version: 2.5 uid resource held maxheld barrier limit failcnt 200: kmemsize 9309653 13357056 14372700 14790164 0 lockedpages 0 1008 2048 2048 0 privvmpages 675424 686528 1048576 1572864 0 shmpages 33 673 21504 21504 0 dummy 0 0 9223372036854775807 9223372036854775807 0 numproc 49 90 240 240 0 physpages 243761 246945 0 9223372036854775807 0 vmguarpages 0 0 1048576 1048576 0 oomguarpages 81672 83305 1048576 1048576 0 numtcpsock 6 8 360 360 0 numflock 175 188 512 512 8 numpty 1 9 16 16 0 numsiginfo 0 48 256 256 0 tcpsndbuf 104640 263912 1720320 2703360 0 tcprcvbuf 98304 131072 1720320 2703360 0 othersockbuf 32368 89304 1126080 2097152 0 dgramrcvbuf 0 2312 262144 262144 0 numothersock 19 28 360 360 0 dcachesize 2285052 3624426 3409920 3624960 0 numfile 616 870 9312 9312 0 dummy 0 0 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 numiptent 24 24 128 128 0

    Read the article

  • Which statically typed languages support intersection types for function return values?

    - by stakx
    Initial note: This question got closed after several edits because I lacked the proper terminology to state accurately what I was looking for. Sam Tobin-Hochstadt then posted a comment which made me recognise exactly what that was: programming languages that support intersection types for function return values. Now that the question has been re-opened, I've decided to improve it by rewriting it in a (hopefully) more precise manner. Therefore, some answers and comments below might no longer make sense because they refer to previous edits. (Please see the question's edit history in such cases.) Are there any popular statically & strongly typed programming languages (such as Haskell, generic Java, C#, F#, etc.) that support intersection types for function return values? If so, which, and how? (If I'm honest, I would really love to see someone demonstrate a way how to express intersection types in a mainstream language such as C# or Java.) I'll give a quick example of what intersection types might look like, using some pseudocode similar to C#: interface IX { … } interface IY { … } interface IB { … } class A : IX, IY { … } class B : IX, IY, IB { … } T fn() where T : IX, IY { return … ? new A() : new B(); } That is, the function fn returns an instance of some type T, of which the caller knows only that it implements interfaces IX and IY. (That is, unlike with generics, the caller doesn't get to choose the concrete type of T — the function does. From this I would suppose that T is in fact not a universal type, but an existential type.) P.S.: I'm aware that one could simply define a interface IXY : IX, IY and change the return type of fn to IXY. However, that is not really the same thing, because often you cannot bolt on an additional interface IXY to a previously defined type A which only implements IX and IY separately. Footnote: Some resources about intersection types: Wikipedia article for "Type system" has a subsection about intersection types. Report by Benjamin C. Pierce (1991), "Programming With Intersection Types, Union Types, and Polymorphism" David P. Cunningham (2005), "Intersection types in practice", which contains a case study about the Forsythe language, which is mentioned in the Wikipedia article. A Stack Overflow question, "Union types and intersection types" which got several good answers, among them this one which gives a pseudocode example of intersection types similar to mine above.

    Read the article

  • linux thread synchronization

    - by johnnycrash
    I am new to linux and linux threads. I have spent some time googling to try to understand the differences between all the functions available for thread synchronization. I still have some questions. I have found all of these different types of synchronizations, each with a number of functions for locking, unlocking, testing the lock, etc. gcc atomic operations futexes mutexes spinlocks seqlocks rculocks conditions semaphores My current (but probably flawed) understanding is this: semaphores are process wide, involve the filesystem (virtually I assume), and are probably the slowest. Futexes might be the base locking mechanism used by mutexes, spinlocks, seqlocks, and rculocks. Futexes might be faster than the locking mechanisms that are based on them. Spinlocks dont block and thus avoid context swtiches. However they avoid the context switch at the expense of consuming all the cycles on a CPU until the lock is released (spinning). They should only should be used on multi processor systems for obvious reasons. Never sleep in a spinlock. The seq lock just tells you when you finished your work if a writer changed the data the work was based on. You have to go back and repeat the work in this case. Atomic operations are the fastest synch call, and probably are used in all the above locking mechanisms. You do not want to use atomic operations on all the fields in your shared data. You want to use a lock (mutex, futex, spin, seq, rcu) or a single atomic opertation on a lock flag when you are accessing multiple data fields. My questions go like this: Am I right so far with my assumptions? Does anyone know the cpu cycle cost of the various options? I am adding parallelism to the app so we can get better wall time response at the expense of running fewer app instances per box. Performances is the utmost consideration. I don't want to consume cpu with context switching, spinning, or lots of extra cpu cycles to read and write shared memory. I am absolutely concerned with number of cpu cycles consumed. Which (if any) of the locks prevent interruption of a thread by the scheduler or interrupt...or am I just an idiot and all synchonization mechanisms do this. What kinds of interruption are prevented? Can I block all threads or threads just on the locking thread's CPU? This question stems from my fear of interrupting a thread holding a lock for a very commonly used function. I expect that the scheduler might schedule any number of other workers who will likely run into this function and then block because it was locked. A lot of context switching would be wasted until the thread with the lock gets rescheduled and finishes. I can re-write this function to minimize lock time, but still it is so commonly called I would like to use a lock that prevents interruption...across all processors. I am writing user code...so I get software interrupts, not hardware ones...right? I should stay away from any functions (spin/seq locks) that have the word "irq" in them. Which locks are for writing kernel or driver code and which are meant for user mode? Does anyone think using an atomic operation to have multiple threads move through a linked list is nuts? I am thinking to atomicly change the current item pointer to the next item in the list. If the attempt works, then the thread can safely use the data the current item pointed to before it was moved. Other threads would now be moved along the list. futexes? Any reason to use them instead of mutexes? Is there a better way than using a condition to sleep a thread when there is no work? When using gcc atomic ops, specifically the test_and_set, can I get a performance increase by doing a non atomic test first and then using test_and_set to confirm? *I know this will be case specific, so here is the case. There is a large collection of work items, say thousands. Each work item has a flag that is initialized to 0. When a thread has exclusive access to the work item, the flag will be one. There will be lots of worker threads. Any time a thread is looking for work, they can non atomicly test for 1. If they read a 1, we know for certain that the work is unavailable. If they read a zero, they need to perform the atomic test_and_set to confirm. So if the atomic test_and_set is 500 cpu cycles because it is disabling pipelining, causes cpu's to communicate and L2 caches to flush/fill .... and a simple test is 1 cycle .... then as long as I had a better ratio of 500 to 1 when it came to stumbling upon already completed work items....this would be a win.* I hope to use mutexes or spinlocks to sparilngly protect sections of code that I want only one thread on the SYSTEM (not jsut the CPU) to access at a time. I hope to sparingly use gcc atomic ops to select work and minimize use of mutexes and spinlocks. For instance: a flag in a work item can be checked to see if a thread has worked it (0=no, 1=yes or in progress). A simple test_and_set tells the thread if it has work or needs to move on. I hope to use conditions to wake up threads when there is work. Thanks!

    Read the article

  • Using Extended Events in SQL Server Denali CTP1 to Map out the TransactionLog SQL Trace Event EventSubClass Values

    - by Jonathan Kehayias
    John Samson ( Blog | Twitter ) asked on the MSDN Forums about the meaning/description for the numeric values returned by the EventSubClass column of the TransactionLog SQL Trace Event.  John pointed out that this information is not available for this Event like it is for the other events in the Books Online Topic ( TransactionLog Event Class ), or in the sys.trace_subclass_values DMV.  John wanted to know if there was a way to determine this information.  I did some looking and found...(read more)

    Read the article

  • Help me finding dependency list.

    - by Pearl
    I have two table employee table and employee dependency table. Employee tooks like below. insert into E values(1,'Adam') insert into E values(2,'Bob') insert into E values(3,'Candy') insert into E values(4,'Doug') insert into E values(5,'Earl') insert into E values(6,'Fran') Employee dependency table looks like below insert into Ed values(3,'2') insert into Ed values(3,'5') insert into Ed values(2,'1') insert into Ed values(2,'4') insert into Ed values(5,'6') I need to find the dependency list like below Eid Ename Dname 3 Candy Bob,Fran Please help me finding the above.

    Read the article

  • Serialized values or separate table, which is more efficient?

    - by Aravind
    I have a Rails model email_condition_string with a word column in it. Now I have another model called request_creation_email_config with the following columns admin_filter_group:references vendor_service:references email_condition_string:references email_condition_string has many request_creation_email_config and request_creation_email_config belongs to email_condition_string. Instead of this model a colleague of mine is suggesting that strong the word inside the same model as comma separated values is efficient than storing as a separate model. Is that alright?

    Read the article

  • How to populate values in drop down from select query on other dropdown?

    - by jacksantho
    How can i populate the values in the drop down(second drop down) from the select query on choosing the option from the first drop down ? Examples: First Drop Down : Listing out all the "department name" using select query. Second Drop Down : Now, i need the output to list out all the "professors name" in the respective departments on the basis of the first drop down option. Thanks in advance. Much Appreciated your help.

    Read the article

  • How to reference or vlookup a list of values based on a comma separated list of column references within a cell in excel?

    - by glallen
    I want to do a vlookup (or similar) against a column which is a list of values. This works fine for looking up a value from a single row, but I want to be able to look up multiple rows, sum the results, and divide by the number of rows referenced. For example: A B C D E F G [----given values----------------] [Work/Auth] [sum(vlookup(each(G),table,5)) /count(G)] [given vals] 1 Item Authorized OnHand Working Operational% DependencyOR% Dependencies 2 A 1 1 1 1 .55 B 3 B 10 5 5 .50 .55 C,D 4 C 100 75 50 .50 .60 D 5 D 10 10 6 .60 1 I want to be able to show an Operational Rate, and an operational rate of the systems each system depends on (F). In order to get a value for F, I want to sum over each value in column-E that was referenced by a dependency in column-G then divide by the number of dependencies in G. Column-G can have varying lengths, and will be a comma separated list of values from column-A. Is there any way to do this in excel?

    Read the article

  • Normalisation and 'Anima notitia copia' (Soul of the Database)

    - by Phil Factor
    (A Guest Editorial for Simple-Talk) The other day, I was staring  at the sys.syslanguages  table in SQL Server with slightly-raised eyebrows . I’d just been reading Chris Date’s  interesting book ‘SQL and Relational Theory’. He’d made the point that you’re not necessarily doing relational database operations by using a SQL Database product.  The same general point was recently made by Dino Esposito about ASP.NET MVC.  The use of ASP.NET MVC doesn’t guarantee you a good application design: It merely makes it possible to test it. The way I’d describe the sentiment in both cases is ‘you can hit someone over the head with a frying-pan but you can’t call it cooking’. SQL enables you to create relational databases. However,  even if it smells bad, it is no crime to do hideously un-relational things with a SQL Database just so long as it’s necessary and you can tell the difference; not only that but also only if you’re aware of the risks and implications. Naturally, I’ve never knowingly created a database that Codd would have frowned at, but around the edges are interfaces and data feeds I’ve written  that have caused hissy fits amongst the Normalisation fundamentalists. Part of the problem for those who agonise about such things  is the misinterpretation of Atomicity.  An atomic value is one for which, in the strange virtual universe you are creating in your database, you don’t have any interest in any of its component parts.  If you aren’t interested in the electrons, neutrinos,  muons,  or  taus, then  an atom is ..er.. atomic. In the same way, if you are passed a JSON string or XML, and required to store it in a database, then all you need to do is to ask yourself, in your role as Anima notitia copia (Soul of the database) ‘have I any interest in the contents of this item of information?’.  If the answer is ‘No!’, or ‘nequequam! Then it is an atomic value, however complex it may be.  After all, you would never have the urge to store the pixels of images individually, under the misguided idea that these are the atomic values would you?  I would, of course,  ask the ‘Anima notitia copia’ rather than the application developers, since there may be more than one application, and the applications developers may be designing the application in the absence of full domain knowledge, (‘or by the seat of the pants’ as the technical term used to be). If, on the other hand, the answer is ‘sure, and we want to index the XML column’, then we may be in for some heavy XML-shredding sessions to get to store the ‘atomic’ values and ensure future harmony as the application develops. I went back to looking at the sys.syslanguages table. It has a months column with the months in a delimited list January,February,March,April,May,June,July,August,September,October,November,December This is an ordered list. Wicked? I seem to remember that this value, like shortmonths and days, is treated as a ‘thing’. It is merely passed off to an external  C++ routine in order to format a date in a particular language, and never accessed directly within the database. As far as the database is concerned, it is an atomic value.  There is more to normalisation than meets the eye.

    Read the article

  • Where can I get a list or data base of light reflectance values for different materials?

    - by mikidelux
    I'm implementing lighting for a WebGL app but I'm not an artist so I don't know how to generate or where to obtain a list of materials with its values (diffuse, specular, ambient and shininess). I've been searching a lot but with no luck. Is there any list or DB I might have overlooked? Any common repository or something similar? Thanks in advance. Note: English is not my main language, let me know if you don't understand something and I'll try to rephrase it.

    Read the article

  • Is it correct to add booleans in order to count the number of true values in a vector?

    - by gerrit
    Is it conceptually correct to sum a vector of booleans? From a mathematical point of view, I would argue it's not: True + True != 2. But it's quite practical to do so still! Example using the vectorised Python library numpy: In [1]: X = rand(10) In [2]: large = X>0.6 In [3]: large.dtype Out[3]: dtype('bool') In [4]: large.sum() Out[4]: 7 I don't like it, but it's very practical. Is this a good practice? Update: the aim is to count the number of true values in a vector.

    Read the article

  • strange array in php

    - by tunpishuang
    here i wrote a function , it's general purpose is to get an array of the depIds under the parent root $depId. i use recursion method to get the array. public function getEmpsByDep($depId){ $query = "select * from ".SQLPREFIX."department where id_parent=".$depId; $stmt=$this->db->query($query); while(($row=$this->db->fetch_assoc($stmt))==true) { if($this->hasChildNode($row['DEPID'])) { $depId = $row['DEPID']; self::getEmpsByDep($depId); } else { $arr[]=$row['DEPID']; } } return ($arr); } while i think it should return a 1D array of the depid.but it return a strange 2D array like this: array(4) { [0]=> string(2) "11" [1]=> string(2) "12" [2]=> string(2) "13" [3]=> string(2) "14" } array(3) { [0]=> string(2) "19" [1]=> string(2) "20" [2]=> string(2) "21" } array(3) { [0]=> string(2) "15" [1]=> string(2) "16" [2]=> string(2) "17" } array(8) { [0]=> string(1) "2" [1]=> string(1) "4" [2]=> string(1) "5" [3]=> string(1) "6" [4]=> string(1) "7" [5]=> string(1) "8" [6]=> string(1) "9" [7]=> string(2) "10" } here is the table structure and data sample: $query[]="create table ".$sqltblpre."department( depId number(10) not null primary key, depName varchar2(50) not null, id_parent number(10) )"; //department(?????) $index=1; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'??',0)"; //1 $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',0)"; //2 $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',0)"; //3 $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',0)"; //4 $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',0)"; //5 $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',0)"; //6 $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'?????',0)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'????',0)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'????',0)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'????',0)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'??',1)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'??',1)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',1)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'??',1)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'??',3)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',3)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',3)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',3)"; //18 $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'??',18)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'???',18)"; $query[] = "INSERT INTO ".$sqltblpre."department values(".$index++.",'??',18)"; so in a word, how can i get the 1D array thought the right code of this function?

    Read the article

  • SQL SERVER – Use ROLL UP Clause instead of COMPUTE BY

    - by pinaldave
    Note: This upgrade was test performed on development server with using bits of SQL Server 2012 RC0 (which was available at in public) when this test was performed. However, SQL Server RTM (GA on April 1) is expected to behave similarly. I recently observed an upgrade from SQL Server 2005 to SQL Server 2012 with compatibility keeping at SQL Server 2012 (110). After upgrading the system and testing the various modules of the application, we quickly observed that few of the reports were not working. They were throwing error. When looked at carefully I noticed that it was using COMPUTE BY clause, which is deprecated in SQL Server 2012. COMPUTE BY clause is replaced by ROLL UP clause in SQL Server 2012. However there is no direct replacement of the code, user have to re-write quite a few things when using ROLL UP instead of COMPUTE BY. The primary reason is that how each of them returns results. In original code COMPUTE BY was resulting lots of result set but ROLL UP. Here is the example of the similar code of ROLL UP and COMPUTE BY. I personally find the ROLL UP much easier than COMPUTE BY as it returns all the results in single resultset unlike the other one. Here is the quick code which I wrote to demonstrate the said behavior. CREATE TABLE tblPopulation ( Country VARCHAR(100), [State] VARCHAR(100), City VARCHAR(100), [Population (in Millions)] INT ) GO INSERT INTO tblPopulation VALUES('India', 'Delhi','East Delhi',9 ) INSERT INTO tblPopulation VALUES('India', 'Delhi','South Delhi',8 ) INSERT INTO tblPopulation VALUES('India', 'Delhi','North Delhi',5.5) INSERT INTO tblPopulation VALUES('India', 'Delhi','West Delhi',7.5) INSERT INTO tblPopulation VALUES('India', 'Karnataka','Bangalore',9.5) INSERT INTO tblPopulation VALUES('India', 'Karnataka','Belur',2.5) INSERT INTO tblPopulation VALUES('India', 'Karnataka','Manipal',1.5) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Mumbai',30) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Pune',20) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Nagpur',11 ) INSERT INTO tblPopulation VALUES('India', 'Maharastra','Nashik',6.5) GO SELECT Country,[State],City, SUM ([Population (in Millions)]) AS [Population (in Millions)] FROM tblPopulation GROUP BY Country,[State],City WITH ROLLUP GO SELECT Country,[State],City, [Population (in Millions)] FROM tblPopulation ORDER BY Country,[State],City COMPUTE SUM([Population (in Millions)]) BY Country,[State]--,City GO After writing this blog post I continuously feel that there should be some better way to do the same task. Is there any easier way to replace COMPUTE BY? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • To Create a Search, with values from multiple selection element?

    - by Harish
    I am working in PHP(with Symfony Framework) and i want to create a search based on multiple values selected from multiple selection element, i.e there will be multiple selection dropdown elements for like countries, cities, age etc.. and the values from them will query a data table and give the desired search output. (all values are not mandatory, will work with atleast one value). the idea will also do..

    Read the article

  • Preserving alpha issues with loaded UIImages - how to avoid discarding alpha values on import?

    - by Peter Hajas
    My application lets the user save/load images with alpha values to the camera roll on the device. I can see in the Photos application that these images are appropriately alpha'd, as alpha'd areas just appear black. However, when I load these images back into the application using the valueForKey:UIImagePickerControllerOriginalImage message to the info dictionary from (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info, the alpha values are turned to just white, making those sections opaque. Is there a way to preserve these alpha values?

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 81 82 83 84 85 86 87 88 89 90 91 92  | Next Page >