Unresolved setelement during substitution

[TomSteu]

Dear FORM team,

I've encountered a curious issue today, I wrote some code that terminated a long computation with Unresolved setelement during substitution. I think this is happening on calling .sort or .end.

Unfortunately, I am quite puzzled by this -- I can get collect a very long list of terms with print "%t"; (print;alone does not work, the error occurs before the output) but I am not sure what to look for in there.

Could you guys give me a hint what this error means, then I can construct some minimal case where things go wrong. Sorry for not providing a sample of code.

cheers, Tom

[tueda]

Well, what I would say for now is maybe: are you using any wildcard substitutions with sets? The error message looks related to something wrong that happened during them.

For your information: the error message is in ResolveSet (wildcard.c)

https://github.com/vermaseren/form/blob/2a37fd21dd22e7f1a90c4956c4adf50555f7bd07/sources/wildcard.c#L1363

which is only called in WildFill:

https://github.com/vermaseren/form/blob/2a37fd21dd22e7f1a90c4956c4adf50555f7bd07/sources/wildcard.c#L611

[vermaseren]

This error occurs typically when you have wildcarding involving set elements as in: Symbols a1,…,a9,x,n; Set aa:a1,…,a9;

id x^n? = aa[n];

If the wildcard n gets a value outside the range 1 to 9 you will get this error message. The safe code would be if ( ( count(x,1) > 0 ) && ( count(x,1) <= 9 ) ); id x^n? = aa[n]; else;

• either print here a message that tells that something unexpected happened
• or continue without the substitution. endif;

I hope this helps.

On 30 Mar 2022, at 18:46, TomSteu @.***> wrote:

Dear FORM team,

I've encountered a curious issue today, I wrote some code that terminated a long computation with Unresolved setelement during substitution. I think this is happening on calling .sort or .end.

Unfortunately, I am quite puzzled by this -- I can get collect a very long list of terms with print "%t"; (print;alone does not work, the error occurs before the output) but I am not sure what to look for in there.

Could you guys give me a hint what this error means, then I can construct some minimal case where things go wrong. Sorry for not providing a sample of code.

cheers, Tom

— Reply to this email directly, view it on GitHub https://github.com/vermaseren/form/issues/407, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABJPCEXLKSRZAWHWMIO4WULVCSAMXANCNFSM5SCRGLZQ. You are receiving this because you are subscribed to this thread.

[tueda]

This error occurs typically when you have wildcarding involving set elements as in: Symbols a1,…,a9,x,n; Set aa:a1,…,a9; id x^n? = aa[n];

I guess this is a bit different problem: running

Symbols a1,...,a9,x,n;
Set aa:a1,...,a9;
Local F = x^10;
id x^n? = aa[n];
.end

gives a different error:

Array bound check during set substitution
    value is 10
Program terminating at test.frm Line 4 -->

which is in

https://github.com/vermaseren/form/blob/2a37fd21dd22e7f1a90c4956c4adf50555f7bd07/sources/wildcard.c#L1434-L1435

The problem with Unresolved setelement ... occurs before coming the label GotOne. (I have no experience with this error message and have no ideas what the code is doing...)

[TomSteu]

Thank you for the hints, I found my mistake. It was indeed some nonsense with a half-integer set position like this:

Symbols a1,...,a9,n;
CFunction cfun;
Set aa:a1,...,a9;

Local F = cfun(1/2);

id cfun(n?) = aa[n];
.end