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I have a list of (undefined) functions, for example:

{f1[x, y, z], f2[x, y, z], f3[x, y, z]}

and I'd like to display it as

{f1, f2, f3}

therefore hiding the variable dependence in all the outputs. With a single function it's easy, because it suffice to use

Format[f[___]]:= f

In the case of the list, my first idea was to simply plug it inside the format function, meaning:

Format[{f1[___], f2[___], f3[___]}]:= {f1, f2, f3}

but I get the following error "Tag List in MakeBoxes [...] is protected". Another possible idea was using a for cicle:

For[j=1, j<4, j++, Format[Subscript[f, j][___]]:=Subscript[f, j]]

but the output was {f_3, f_3, f_3}.

Is there another way to display lists differently? I know that a function called ListFormat exists, but it seems not to work either. Probably one could Unprotect the List, but I have no idea how to reformat the whole thing then.

Thanks in advance for your help!

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    $\begingroup$ You could create the formatting rule for each symbol, e.g. Format[f1[___]] := f1 (and similarly for f2, f3). Or you could just use Head: Head /@ {f1[x, y, z], f2[x, y, z], f3[x, y, z]}. Or Part: {f1[x, y, z], f2[x, y, z], f3[x, y, z]}[[All, 0]]. There are a multitude of ways to do this depending on what format your original list is in and how much control you have over creating it. $\endgroup$ Commented Oct 10, 2024 at 16:18
  • $\begingroup$ Thanks for the answer! So, the first solution would be fine, but I have lists with many entries and I would like to avoid formatting them one by one. Regarding the use of Head: these lists are then used in expressions, therefore I'd like a global function that adjusts everything once and for all. $\endgroup$ Commented Oct 10, 2024 at 16:24

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$Version

(* "14.1.0 for Mac OS X ARM (64-bit) (July 16, 2024)" )

Clear["Global`*"]

Rather than naming functions f1, f2, f3,...; use indexes, e.g., f[1], f[2], f[3],... Then

Format[f[n_]] := Subscript[f, n]

Format[f[n_][___]] := f[n]

{f[1][x, y, z], f[2][x, y, z], f[3][x, y, z]}

enter image description here

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  • $\begingroup$ Thanks a lot for the answer! I had to adapt it a little bit to my needs, but it works perfectly! $\endgroup$ Commented Oct 13, 2024 at 12:19

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