Defining a function from $\mathbb {R}$^p to $\mathbb {R}$

For p = 1, e.g. for f  :  (x) $\rightarrow$ x*sin(x), input :

f(x):=x*sin(x)

Or :

f:=x->x*sin(x)

Output :

(x)->x*sin(x)

If p > 1, e.g. for f  :  (x, y) $\rightarrow$ x*sin(y), input :

f(x,y):=x*sin(y)

Or :

f:=(x,y)->x*sin(y)

Output :

(x,y)->x*sin(y)

Warning !!! the expression after -> is not evaluated. You should use unapply if you expect the second member to be evaluated before the function is defined.