Re: XML Schema - C# Discussion Boards

Pre-Build events for specific configurations

6-Oct-03 9:08

look at the Data COmmandBuilder classes, should provide the schema for u, dunno about oracle as u need a phd (and a small atomic powerplant) to work with it.

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Joe Woodbury6-Oct-03 8:42

Joe Woodbury

6-Oct-03 8:42

For our Beta builds, I need to run a command line program just before building the main assembly. Yet the only pre-build setting I can find runs it for ALL configurations.

(I modified the utilities in question to accept a parameter of $(configuration name). Of course, this means the utilities have to now be build and for all configurations. Who's the idiot who came up with this limitation?)

Joe Woodbury

When all else fails, there's always delusion.
- Conan O'Brien

Re: Pre-Build events for specific configurations

leppie6-Oct-03 9:21

Re: Pre-Build events for specific configurations

6-Oct-03 9:21

use the ol' empty C++ project trick Smile | :)

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Joe Woodbury6-Oct-03 9:39

Joe Woodbury

6-Oct-03 9:39

Good idea. Thanks.

Joe Woodbury

When all else fails, there's always delusion.
- Conan O'Brien

Statistical Functions in C#

AZBugsBunny6-Oct-03 8:00

AZBugsBunny

6-Oct-03 8:00

I would like to know if there is any built in function/library in C# which lets me solve the foll. Statistical problem:
Given the mean and the variance of a normal distribution, I want to get the sample points that are arrived at based on the mean and variance.
(Basically some function similar to the Worksheet function NormInv in MSExcel).
Right now I am doing a very kludgy solution where I create an Excel Worksheet function object just to access the function. This makes my application real slow. Frown | :(

Moreover I need this type of evaluation to be done possibly 10,000 times as I am developing some kind of a simulator.
Anybody please help !!!!

leppie6-Oct-03 9:28

6-Oct-03 9:28

Those methods wouldnt be hard at all to implement in a class or two. In fact thats a good idea for your 1st article here at CodeProject. Smile | :)

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Kevin McFarlane6-Oct-03 10:37

Kevin McFarlane

6-Oct-03 10:37

I'm sure I remember there being a C# math library on the web somewhere - probably not free though and I can't remember what it was called or whether it supported stats.

Ah, just did a search and there's one here: http://www.centerspace.net/products.php?page=3[^]

The stats library is released next month.

Kevin

leppie6-Oct-03 12:31

6-Oct-03 12:31

Now that kevin mentioned it. Do a search for Math.NET and Euler.NET on SOurceforge, both provide stats functions i think.

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Donald_a8-Oct-03 3:40

Donald_a

8-Oct-03 3:40

I'm not sure exactly what you are after, but this may help?

using System;

namespace NormInvFunc{

	public class Normal
	{         
	        private static double Density(double x)
		{
			double y=Math.Pow (2*Math.PI ,-.5)*Math.Exp(-.5*x*x);
			return y;
		}

		public static double StandardNormal(double x)
		{
			double [] a=new double[5];
			a[0]=.31938153;
			a[1]=-.356563782;
			a[2]=1.781477937;
			a[3]=-1.821255978;
			a[4]=1.330274429;
 
			double K=.2316419;
			double L=Math.Abs(x);
			double nx=Density(L);
			double q=1/(1+K*L);
			double S=0;
			for(int j=0;j<5;j++)
			{
				S+= a[j]*Math.Pow(q,j+1);
			}
			double SND=1-nx*S;
			if(x<0)
			{
				SND=1-SND;
			}
			return SND;
 
		}
                                                               
		public static double StandardNormalInv(double R)
		{
			double Delta=1;
			double X=0;
			double Y=0;
			do
			{
				Y=X-(StandardNormal(X)-R)/Density(X);
				Delta=Math.Abs (Y-X);
				X=Y;
			}
			while (Delta>.000000001);
 
			return Y;
 		}
 
	}
 
}

NB will not return quite as many decimal places as excel.

about lock

yyf6-Oct-03 5:52

yyf

6-Oct-03 5:52

I am try to use multi-thread. I use "lock" like this:

class MyClass<br />
{<br />
  private object status = null; <br />
<br />
<br />
  myfun() {<br />
   ...<br />
   lock ( status ) {<br />
     status = new object(1);<br />
   }<br />
   ...<br />
  }<br />
}

But it gave me an "ArgumentNullException", anyone know why?

Thanks in advance.

jparsons6-Oct-03 6:21

jparsons

6-Oct-03 6:21

You need an actual object to lock.
yyf wrote:
private object status = null

Change line into

private object status = new object()<br />
<br />
And everything will be happy.  But then again I'm not sure why you're trying to create the object inside of the lock.  <br />
<br />
Jared <br />
<a>jparsons@jparsons.org</a><br />
<a href="http://www.prism.gatech.edu/~gte477n">www.prism.gatech.edu/~gte477n</a>

Help me dominate the world - click this link and my army will grow

Daniel Turini6-Oct-03 6:30

Daniel Turini

6-Oct-03 6:30

Maybe he's trying to make a late initialization for some reason, and wants to prevent it to be initialized two times. If that's the case, what he needs is a second variable to protect the access to status, or initializing it the way you described.

jparsons6-Oct-03 6:36

jparsons

6-Oct-03 6:36

Or he can just use a static constructor.

Jared
jparsons@jparsons.org
www.prism.gatech.edu/~gte477n

yyf6-Oct-03 7:39

yyf

6-Oct-03 7:39

Thanks for all your response. Sorry, I didn't make myself clear.

Actually I want to change the value of status in the lock block. I need to lock it in case some one else are using it.

so it should be something like that:

class MyClass<br />
{<br />
<br />
private object status = null;<br />
private object status0 = new object(0);<br />
private object status1 = new object(1);<br />
private object status2 = new object(2);<br />
<br />
myfunc()<br />
{<br />
...<br />
lock ( status ) {<br />
status = status1;<br />
}<br />
...<br />
}<br />
<br />
}

It has problem as I mentioned.

Maybe I should change it to:

status = new object(0);<br />
lock ( status )<br />
{<br />
status = status1;<br />
}

Another quick question:
From the help in .Net, it suggests I can use either this or typeof(class). But I don't understand how to use "typeof(class)"; I tried "lock ( this )", it worked. But I wonder how about if I have different variables in one class to protect. If I use "lock (this)", it'll bring up some unnecessary blocks. Right? So what should I do in this case?

Thank you very much.

jparsons6-Oct-03 13:02

jparsons

6-Oct-03 13:02

yyf wrote:
1: status = new object(0);
2: lock ( status )
3: {
4: status = status1;
5: }

I've added line numbers for clarification

This function will not work as you expect it to. For example assume I have two instances of MyClass m1 and m2. Each are created in a seperate thread. m1 executes lines 1-4 and then there is a thread switch. The problem is now the lock is on the previous object status pointed to and there is virtually no way to retrieve that object. Now m2 comes along and executes line 1 and 2. It is locking a completely new object so even though the thread containing m1 is currently inside the lock, the thread containing m2 will proceed into the code block. Now event though status1 will be set correctly in your case, the code is misleading and incorrect.

The easier way to do this is through a property and a locking object.

<br />
public class MyClass<br />
{<br />
  private static object Sync = new object();<br />
  public static object _status = null;<br />
<br />
  public static object status<br />
  {<br />
    get <br />
    {  <br />
      lock ( Sync )<br />
      { <br />
        if ( _status == null ) <br />
        { <br />
          _status = new object();<br />
        }<br />
      }<br />
      return _status;<br />
    }<br />
   }<br />
   /* Rest of Class */<br />
}<br />

Or you can just use a static constructor.

Jared
jparsons@jparsons.org
www.prism.gatech.edu/~gte477n