Delegates and Parallel.For - C# Discussion Boards

Re: Abort a suspended thread

25-May-09 2:07

You could undo it after. See my reply.

Fahad Sadah25-May-09 2:05

Delegates and Parallel.For

25-May-09 2:05

try
{
    yourThread.Abort();
}
catch (ThreadStateException e)
{
    yourThread.Resume();
}

Fahad Sadah25-May-09 1:25

25-May-09 1:25

for (number=0;primes<10001;number++)

That is a valid for loop.
However, I am trying to parallelize this, and Parallel.For will only accept one delegate.
Therefore, if I wanted

for (number=0;number<10001;number++)

I could do

Parallel.For(0,10001, delegate(int number))

Parallel.For has no overload which accepts two delegates.
What is the Parallel.For equivalent of the first snippet?
Thanks,
Fahad Sadah

S. Senthil Kumar25-May-09 3:38

S. Senthil Kumar

25-May-09 3:38

Fahad Sadah wrote:
for (number=0;primes<10001;number++)

If primes doesn't change in the body of the loop, why doesn't

Fahad Sadah wrote:
Parallel.For(0,10001, delegate(int number))

work?

Regards
Senthil [MVP - Visual C#]
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harold aptroot25-May-09 3:39

harold aptroot

25-May-09 3:39

It probably does though. Why else would he have asked?

S. Senthil Kumar25-May-09 3:52

S. Senthil Kumar

25-May-09 3:52

Well, if it does, the code isn't really parallelizable. If each iteration of the for loop overwrites the variable in a way that is dependent on previous iterations, it doesn't really make sense to parellilize it. For example, if it really is calculation of primes, then numbers = 10000 could run before numbers = 2.

Regards
Senthil [MVP - Visual C#]
_____________________________
My Home Page |My Blog | My Articles | My Flickr | WinMacro

Fahad Sadah25-May-09 7:26

25-May-09 7:26

Impossible?

Thanks.

Accessing the right Registry entry for Internet Explorer in C#

Nicholas Butler25-May-09 7:54

Nicholas Butler

25-May-09 7:54

Good question!

The problem you have is that you don't know the bounds of your input - you don't know how big number will have to get to generate the required number of primes.

However, you can still parellelise chunks of work - something like this:

const int N = ( int ) 1e6;
static readonly int STEP = Environment.ProcessorCount * ( int ) 1e6;

...

var primes = new List<int>( N );

for ( int start = 2 ; primes.Count < N ; start += STEP )
  primes.AddRange(
    Enumerable.Range( start, STEP )
    .AsParallel().AsOrdered()
    .Where( i => IsPrime( i ) ) );

primes = primes.Take( N ).ToList();

You'll have to tune the values of N and STEP for your specific case.

Nick

----------------------------------
Be excellent to each other Smile | :)

Slide bar

yesu prakash25-May-09 1:18

yesu prakash

25-May-09 1:18

Hi,
In an application playing number of files from a folder, i need to use slide bar.
How can i implement in my application. I am using 2005 framework.

Thankyou,
YPKI

Re: Slide bar

Eduard Keilholz25-May-09 3:37

Eduard Keilholz

25-May-09 3:37

What do you want the slidebar to look like, and even more important, what do you want the slide bar to represent?

.: I love it when a plan comes together :.
http://www.zonderpunt.nl

ramz_g25-May-09 1:05

ramz_g

25-May-09 1:05

Hi,

I am working on a small application that checks what browsers are installed on a system running Windows Xp... I was able to find the right entries to check whether Firefox and Chrome are installed or not... And after quite some amount of googling about IE, I found that IE might get corrupted due to some unforeseen reasons... So, is there a possibility of a windows system to have NO internet explorer installed? If yes, How can I check whether IE is present or not.. Please suggest...

Thanks in Advance

Re: Accessing the right Registry entry for Internet Explorer in C#

Rajesh R Subramanian25-May-09 4:03

Rajesh R Subramanian

25-May-09 4:03

IE is a part of Windows itself and you can safely assume its existence on Windows. I personally won't go bothering about an usecase where the IE installation is corrupt for some unforeseen reasons. It may be negligible.

It is a crappy thing, but it's life -^ Carlo Pallini

XmlTextWriter and MemoryStream

OriginalGriff25-May-09 1:05

OriginalGriff

25-May-09 1:05

Is there any way to get a XmlTextWriter to work with a MemoryStream, so that it doesn't close it when it is finished?
What I'm trying to do is:
List<T> -> MemoryStream (as XML) -> TripleDES encyrption -> file.
And later:
file -> TripleDES decryption -> MemoryStream -> List<T>

And since XmlTextWriter always closes the stream when it completes, the MemoryStream is useless!
Yes, XMLTextWriter has settings, but they are null or read-only, so you can't set "CloseOutput = false"

(No, I don't want to use XMLSerialiser, for very dull reasons!)

I have got round it by moving to XmlWriter and using the settings that way, but this was such a waste of time!

Old way:

WriteXML(listCards, new XmlTextWriter(stream, Encoding.UTF8));
if (stream.CanSeek)
    {
    stream.Seek(0, 0);
    }

New way:

XmlWriterSettings settings = new XmlWriterSettings();
settings.OmitXmlDeclaration = false;
settings.ConformanceLevel = ConformanceLevel.Document;
settings.CloseOutput = false;
settings.Indent = true;
settings.Encoding = Encoding.UTF8;
WriteXML(listCards, XmlWriter.Create(stream, settings));
if (stream.CanSeek)
    {
    stream.Seek(0, 0);
    }

No trees were harmed in the sending of this message; however, a significant number of electrons were slightly inconvenienced.

This message is made of fully recyclable Zeros and Ones

7.1 Surround Sound

Chris MacEwan25-May-09 0:51

Chris MacEwan

25-May-09 0:51

Hi,

Does anyone know a way I could simulate 7.1 channel surround sound with DirectX? Our school is doing the Wizard of Oz as the school play this year, and as part of it, we want the tornado to move around the Audience, we have speakers in the right spots, and the everything we need to drive them, its just we need to be able to move the sounds around and make them feel realistic to the audience.

So in short, does anyone know how I could set up 7 listening devices in DirectSound or XNA so that the levels change for each speaker as the virtual speaker moves throughout the audience.

And here's a crude drawing of the idea: http://img30.imageshack.us/img30/3246/tornadopath.jpg[^] (each speaker group represents a different channel)

Re: 7.1 Surround Sound

molesworth25-May-09 2:18

molesworth

25-May-09 2:18

DirectSound does support 7.1 - set the speaker config to DSSPEAKER_7POINT1_SURROUND. (Or to DSSPEAKER_7POINT1 if you haven't gone up to XP SP2 yet.)

Then it should be just a matter of moving the sound source around the listener location, and Dorothy's your auntie...

There are three kinds of people in the world - those who can count and those who can't...

open aspx page

michaelgr125-May-09 0:50

michaelgr1

25-May-09 0:50

Hello,
How can i open aspx webpage using c# window application?
I mean not using "System.Diagnostics.Process.Start"
but another way so i can check if there is such webpage (try...catch.. or something)

padmanabhan N25-May-09 1:31

padmanabhan N

25-May-09 1:31

//in windows application there is no such thing as aspx page.
//in web application we can open a aspx page as,

Response.Redirect("Sample.aspx");
(or)
server.trasfer("Sample.aspx");

//you can open a form using windows appliaction like,

Form2 frm = new Form2();
frm.Show();

Padmanabhan

michaelgr125-May-09 1:32

michaelgr1

25-May-09 1:32

Yes,
But i have aspx on the net (as URL). How can i open it in browser?

Ramesh Swaminathan25-May-09 3:22

Ramesh Swaminathan

25-May-09 3:22

You can do it using HttpWebResponse in the System.Net namespace.

Refer this link[^]