Symbol Meaning: \vdots Susceptibility Electric Field

[n0_3sc]

What symbol is this??

What does this mean " $$\vdots$$ "

I don't what its called so I couldn't google it...Its to do with Susceptibility and Electric Field.

 

[n0_3sc]

(The symbol inside the quotation marks)

 

[ijustlost]

What context was it used in? Might be clearer if you put down the whole equation / sentance it's used in..

 

[n0_3sc]

Its used like this:

$$\overline{P} = \epsilon\chi^{(2)}\vdots\overline{E}$$

(In relation to polarization and susceptibility of an EM wave)