[RESOLVED] Using Delta

[mburr]

Hello,

I want to copy an equation into VB.Net that has the Delta symbol in it. I've tried the Math object, and it doesn't have a Delta method. Does anobody know of a function or an equation that can replace the symbol?

Thanks in advance for your help!

Sincerely,
mburr

[wy125]

you want just the symbol or you want to implement the function? Are you referring to the Dirac's delta function?

[mburr]

Wow, what a quick reply. Anyway, I guess I wasn't being very clear. I need a VB.Net function that has the same effect on the equation as the symbol.

[wy125]

can you describe the delta function that you want in more detail. Do you mean this http://en.wikipedia.org/wiki/Dirac_delta_function? Or do you mean that you want to take the difference between two numbers?

[mburr]

Whichever one has a triangle for a symbol and means that the smallest possible change is the most accurate. Hey, out of curiosity, do you use IncrediMail?

[wy125]

Okay the one with the triangle usually means taking the difference of two values. I'm not sure what the smallest difference would mean because the smallest (absolute) difference for a function would be 0... It sounds like you are trying to numerically compute a derivative whose value would improve when taking smaller and smaller differences. Is this what you're trying to do? If so, then there is no built in method for doing so. Well I guess the '-' operator would do just fine.... You would need to do something like:

1. define a function say f(x)
2. compute the function at a given value a
3. compute the function at another value b so that b is very close (you have to figure out how close you want to be because you can be infinitely close (though you will hit the limit of computable precision)
4. compute the difference f(b) - f(a)


no, i don't use incredimail... Is this a homework assignment?

[mburr]

Okay, for clarification reasons I will post part of the full equation of time. (Here, the ^ will represent Delta instead of "to the power of.")

T = ^T(t)

[wy125]

There is no such operator or built-in function for VB that I'm aware of. It is relatively easy to implement though as long as you are willing to relax the "smallest possible change" idea.

Do you have a function that computes T(t)?

[mburr]

Oh, and you really SHOULD try IncrediMail. I've got it on my computer, and it does actually help me respond faster to any reply to a thread here that I am subscribed to. Every time it checks for new mail & sees that I have some, a cute little puppy runs to the bottom-right corner of the screen, carrying a letter in its mouth. Of course, I CHOSE to have that notifier. Other than the notifier, there are styles you can use to personalize every e-mail you compose. However, nowadays you have to pay Microsoft in order to be able to use Hotmail with an e-mail client.

[mburr]

And no, I don't have a function that computes T(t). I didn't think I needed one.

[wy125]

there is no way to compute the "delta of a function" without first having the function. Do you have it on paper or something?

[mburr]

I've found my solution, yippee for me! Thanks for helping. The answer was in the e-book with the equation in it. Just to clue you in on something, I'm working on a DLL file that performs an algebraic calculation that is necessary for it to work properly. I'm also working on a program that uses the file. Maybe I can make a few bucks out of selling either one.

[wy125]

hmmm an algebraic calc.... sounds interesting... does that mean you are doing symbolic calculations (like keeping things in analytical form)

[mburr]

yep, that WAS the idea.

[wy125]

That's pretty cool. It's generally a difficult problem though some operations are easier than others. You're gonna need a parser of some kind. You may want to check out sourceforge.net (http://sourceforge.net)for similar projects. You may get some good ideas....

[jemidiah]

More than simple symbolic algebra is very difficult to do. Good luck though!

[VBAhack]

http://digilander.libero.it/foxes/mathparser/MathExpressionsParser.htm