Newsgroup sci.math.num-analysis 28933

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Hello you all,
Altough this may not be the right newsgroup I'll send to this group too
perhaps someone can help me. 
I have to solve the following integration, who can help me or give me
some hints?
I(t) =  
     A * Integral(from z=zo until oo)  exp(-a*z) * sigma(t - to) dz   
Where:
	zo is the lower and oo (infinite) is the upper integral limit
	A, zo and a are constants  
	to = (z - zo)^2 / D,  with D as a constant  
	sigma is a step function and is defined:   sigma = 0 for t=to
My actual problem is to find a way to integrate the step function sigma.
Is there any possiblities to approximate it to a mathematical function.
Or is there any rule for its integration that I am not aware of it.
I have already looked in some Math books but I didn't find it.
PS.:	Please send me your responses also via e-mail, since I don't read this
	newsgroup everyday.
Thanks in advance
Farzad

In article <329086B8.17E4@sonalysts.com>, Al Gerheim  wrote:
> We need to generate contours from non-uniformly spaced control 
> points. The contours must be smooth, and must pass on the 
> correct side of the control points.  Please direct me to 
> algorithms I can convert into C.  
> 
> 
If the control points are very irregular you could take my ACM
Algorithm 626 from Netlib (a pointer is on my home page). It's
written in FORTRAN but could be easily converted to C. All you
need are routines for "pen moves": up and down. The contours are
smooth and pass exactly where they should.
If the control points are on a rectangular mesh, with just irregular
spacing in either x or y, or bothdirections, that case is handled by
"xfarbe", also available from netlib or from my home page.
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Does anyone know where I can find (on the net) a 3D unstructured mesh
generator for turbulence applications (preferably public domain)?
Many thanks in advance.
E-mail gcoppola@netgroup.it

Does anyone know where I can find (on the net) a 3D unstructured mesh
generator for turbulence applications (preferably public domain)?
Many thanks in advance.
E-mail gcoppola@netgroup.it

	I'm writing my own C++ matrix/vector libraries for simple numerical
analysis. Along the way, I've run into LAPACK++. Mentioning it to someone
else, he told me that he had some numerical problems with it. I was
wondering if anyone else out there could either recommend or disrecommend
LAPACK++ based on their experience with it.
	I checked the FAQ at rtfm, but unfortunately there are only two
lines about LAPACK++ being a work in progress and supporting only a subset
of LAPACK's functionality.
	Thanks in advance for your help.
						VTY, Rob Blasi
-- 
| Robert S. Blasi                    |  "The mind is not a vessel to be   |
| Drexel University, B.S.E.E '95     |   filled, but a fire to be lit."   |
| M.S. candidate, Berkeley, Robotics |                   --Plutarch       |
+-----------------http://www.cs.berkeley.edu/~blasirs---------------------+

Gennaro Coppola wrote:
> 
> Does anyone know where I can find (on the net) a 3D unstructured mesh
> generator for turbulence applications (preferably public domain)?
> 
> Many thanks in advance.
> 
> E-mail gcoppola@netgroup.it
You should start your effort at URL:
http://www.cs.cornell.edu/home/vavasis/qmg-home.html
I guess that is only part of what you might find usefull, since
its only the gridgenerator part of your question.
Anyway, hope its a help.
Wolmer Jørgensen.

	Does anyone has the C source code for Mahalanobis distance
calculation? If so, please email me. Or any reference of simple
explanation would do.
					Thanks in advance
						Joe

Jim Hunter  wrote:
>Hyun Min Peck wrote:
>> 
>> In article <576rfd$lqg@electra.saaf.se>, pausch@electra.saaf.se says...
>
>
>> >    void sub( int arr[10] )
>> >    {
>> >        int i;
>> >        for( i = 0; i < sizeof(arr)/sizeof(arr[0]); i++ )
>> >            printf( " %d", arr[i] );
>> >    }
>> >
>> >    main()
>> >    {
>> >        int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
>> >        sub( arr );
>> >    }
>> >
>> >This program does not output  " 1 2 3 4 5 6 7 8 9 10" as one naively
>> >might expect.  Instead it outputs " 1" or " 1 2", depending on the
>> >environment used.....
>> >
>
>> The reason why you are getting the results is that
>> sizeof (arr)/sizeof (arr[0]) = 1 not 10 as you might expect.
>> Try instead i<10, You will get the output "1 2 3 4 5 6 7 8 8 10".
>> 
>
>Yes, of course that's what is happening. But the point is you
>would not expect that to happen -- at least I didn't.
>Add the following in the main routine and see what you get:
>
>	printf("The size is %d\n",sizeof(arr)/sizeof(arr[0]));
>
>I get 10. 
>
>The same line added to the subroutine gives prints 1.
>
>What's happening of course is that C is printing the size of 
>the pointer passed to sub rather than the size of the array
>that is declared as being passed.
It appears that parameters of type array of T are converted
to pointer to T at their point of declaration, and this is because
C does not pass arrays. However, a local or a global variable
of type array of T, does not get converted to pointer to T until
it is used in an expression and if it is not an 
operand to the sizeof operator. I also feel that this is an
inconsistency of the C language and especially since:  "parameters
are understood to be declared just after the beginning of the compound 
statement constituting the function's body" (K&R2; pg, 226). It
will be interesting to see what others think.
  enina- lo
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Marcus  writes:
> I have a number of x,y data points that form an arc of constant radius. 
>  Do you know a good technique for finding the center and radius of the 
> arc?
> I've tried the following, but I'm not sure of it's reliability:
> take first data point, find line running through point but also tangent 
> to the arc, take second data point and find line tangent again.  
But how do you construct a tangent? If your points are not very
closely spaced, that's impossible. Besides, your method will break
down if your points are not exactly on a circle.
I'd suggest a least-squares fit of the data points to the equation
of a circle.
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