Math & Science ⇒ fractions

[willy0625]

Hi. Somehow I cannot produce these fractions properly.

$$f(x)=\displaystyle\frac{2}{\pi}\arctan\Big(\frac{t}{a}\Big)\hspace{4mm}\text{if}\hspace{3mm}x=0,1,\ldots$$

Cheers

[localghost]

Please explain by means of a minimal working example (MWE) what in your eyes appears improper. And take a look at l2tabu why not to use $$...$$ for unnumbered displayed equations.


Best regards and welcome to the board
Thorsten