Mathematica: simplify function notation

Question

I have some calculations with an arbitrary function. In the output, Mathematica always shows the function arguments. I would like to tidy the notation a bit, by hidding the arguments in the output. How can I do that? Or even better, is there a way to write the function arguments just once in the code? Remembering it's an arbitrary function.

For example, its something like this:

f[x,y] + (f[x,y])^2 = ...

And I prefer like this:

f + f^2 = ...

Thanks!

Answer 1

You mean just for display purposes? May be a simple /. ?

Clear[x, y, f]
expr = f[x, y] + (f[x, y])^2 == 34;
expr /. f[__] -> f

gives

Out[29]= f + f^2 == 34

You can even modify $PrePrint to do this automatically

Clear[x,y,f]
$PrePrint=#/.f[__]->f&;
expr=f[x,y]+(f[x,y])^2==34

Out[6]= f+f^2==34

expr
Out[7]= f+f^2==34

To get it back, do

$PrePrint=.
expr

Out[10]= f[x,y]+f[x,y]^2==34

I am not brave enough to do this myself in actual programming, but it is there to try.