Year 12s: what will be the first way you research your future options? >>

Mathematical Notation

Looking at the equation at the top of this page why are there letters in brackets after the differentials? Is it to show that the differentials are functions of the three bracketed letters?

Thanks

Reply 1

jpowell

Your hyperlink is wrong, it should be http://en.wikipedia.org/wiki/Poisson's_equation

Anyway. The equation has a function in three variables, x, y and z.

What the equation is saying is that the second partial derivative of phi of x,y and z with respect to x, plus the second partial deriviative of phi of x, y and z with respect to y plus .... with respect to z is equal to some other function of x, y and z.

So the letters in brackets are part of the function you are differentiating, notifying you that the value of phi depends on x, y and z together.

Hope that makes sense.

Reply 2

terryb

That's exactly it. Remember that f(x) means that f is a function of x's. These are fairly obvious, most of the time!

For more complicated functions it is often useful to know which bits are variables (in this case x, y, z) and which bits are constants.

Reply 3

JaF