What does the single at sign @ mean in mathematica?

Answer 1

The "@" is a shorthand notation for "Prefix". There are three basic ways to apply functions to arguments in Mathematica: Prefix, Infix, and Postfix. The most common of these are Prefix (applied before the argument) and Postfix (applied after the argument):

test = {1, 2, 3}

Total[test] (*Prefix*)

Total@test (*Prefix shorthand*)

test // Total (*Postfix shorthand*)

All three of these will give 6 as the output.

The limitation of the shorthand Prefix and Postfix notations is that they don't work if your function needs more than one argument. E.g., you can do:

Integrate[x^2,x]

But not:

Integrate@x^2, x

or

x^2, x//Integrate