neg
Syntax
neg(X)
Arguments
X is a scalar/pair/vector/matrix.
Though neg
and the 
operator often serve analogous
purposes, precedence behavior differs:

The
neg
function, when parenthesized carries the highest priority, e.g., neg(3) + 5 is 3 + 5. Without parentheses,neg
has lower precedence than the following expression, e.g., neg 3 + 5 is treated as (3 + 5) resulting 8. 
The

operator always follows the precedence rule. For example: 3 + 5 results in 2.
Details
Return the negative of X.
Examples
x=1:2;
x;
// output
1 : 2
x=1 0 1;
x;
// output
[1,0,1]
m=1 1 1 0 0 0 $ 2:3;
m;
#0  #1  #2 

1  1  0 
1  0  0 
m
#0  #1  #2 

1  1  0 
1  0  0 