Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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bobbym
2012-10-22 01:25:47

It looks like it comes from the total derivative but I can not understand their notation so I can not derive it.

zetafunc.
2012-10-21 23:28:31

Hmm. I think maybe that comes from an illustration.

bobbym
2012-10-21 23:05:34

Hi;

Over here he calls it a definition.

http://www.ltcconline.net/greenl/course … iffere.htm

zetafunc.
2012-10-21 22:59:31

As part of the proof, they are saying that

is the total differential of the function f(x,y). Why?

bobbym
2012-10-21 22:44:37

Hi;

Check here about half way down.

zetafunc.
2012-10-21 22:15:51

Thanks. I am particularly confused by the minus sign.

bobbym
2012-10-21 22:03:33

Hi;

That I do not. I will see if I can find anything.

zetafunc.
2012-10-21 21:56:55

Yes, I agree. It was useful for solving the ODEs we were given in class when we had to differentiate annoying functions twice and sub initial conditions, etc... do you remember how it is derived?

bobbym
2012-10-21 21:55:38

Hi zetafunc.;

I know about that one. It is useful for implicit functions.

zetafunc.
2012-10-21 21:11:01

I came across an interesting tool which would help for differentiating functions involving x and y;

where f is a function of x and y and the deltas denote partial derivatives.

But why is this the case?