sorry for the messed up setting of the table, trying again, and adding a 
web-paste

http://ix.io/2qMC

|  date | measure | running avg |
|-------+---------+-------------|
| 01-27 |     604 |             |
| 01-28 |     314 |             |
| 01-29 |     636 |             |
| 01-30 |     305 |             |
| 01-31 |     760 |             |
| 02-01 |     531 |             |
| 02-02 |     331 |      497.29 |
| 02-03 |      77 |      422.00 |
| 02-04 |     621 |      465.86 |
| 02-05 |     406 |      433.00 |
| 02-06 |     621 |      478.14 |
| 02-07 |     975 |      508.86 |
| 02-08 |     252 |      469.00 |
| 02-09 |     794 |      535.14 |
| 02-10 |      36 |      529.29 |
#+TBLFM: $3='(unless (> @# 7) "skipped")
#+TBLFM: $3='(when (> @# 7) (/ (apply #'+ '(@-6$2..$2)) 7.0));N%0.2f
#+TBLFM: $3='(/ (apply #'+ '(@-6$2..$2)) 7.0);N%0.2f::@2$3='(string)::@3$3='(string)::@4$3='(string)::@5$3='(string)::@6$3='(string)::@7$3='(string)

On 03/07/2020 09:53, Mario Frasca wrote:
> hi again,
>
> I haven't found how to solve this, short of removing the evaluation of 
> `user-error' from the org-table.el code, or stuffing my TBLFM line 
> with field formulas.
>
> a very simple use case: three columns: the date, a daily measurement, 
> and a running 4-days average.
>
> |  date | measure | running avg ||-------+---------+-------------|| 
> 01-27 |     604 | skipped || 01-28 |     314 | skipped     || 01-29 
> |     636 | skipped || 01-30 |     305 | skipped     || 01-31 |     
> 760 | skipped || 02-01 |     531 | skipped     || 02-02 |     331 | 
> nil || 02-03 |      77 | nil         || 02-04 |     621 | nil || 02-05 
> |     406 | nil         || 02-06 |     621 | nil || 02-07 |     975 | 
> nil         || 02-08 |     252 | nil || 02-09 |     794 | nil         
> || 02-10 |      36 | nil |#+TBLFM: $3='(unless (> @# 7) "skipped") 
> #+TBLFM: $3='(when (> @# 7) (/ (apply #'+ '(@-6$2..$2)) 7.0));N%0.2f 
> #+TBLFM: $3='(/ (apply #'+ '(@-6$2..$2)) 
> 7.0);N%0.2f::@2$3='(string)::@3$3='(string)::@4$3='(string)::@5$3='(string)::@6$3='(string)::@7$3='(string)
>
> the first TBLFM shows you which cells I'm skipping, that is, where I'm 
> not applying the @-6 reference.  the status of the table results from 
> evaluation of that TBLFM line.
>
> the second TBLFM line skips all @-6 references, but still fails with 
> the message
>
> user-error: Row descriptor -6 leads outside table
>
> the third TBLFM line "solves" the problem, in one of the ugliestests 
> ways.
>
> how would you people approach this?
>
>
> On 29/06/2020 12:03, Mario Frasca wrote:
>> Hi,
>>
>> I need some help understanding how to use org-mode/org-table for 
>> references leading outside my table.
>>
>> I have a series of daily figures, and I am computing the series of 
>> running sums.  column one is the daily data, column two is the 
>> running sum of the preceding 14 values from column 1.
>>
>> http://ix.io/2qu7
>>
>> problem is the @-13$1 reference in the function for the second 
>> column: it hits a software-generated "user-error: Row descriptor -13 
>> leads outside table".
>>
>> this happens even if the formula says (if (> @# 13) (apply '+ 
>> '(@-13$1..$1)) 0), that is, even if the formula is not evaluated on 
>> the cells where the reference does indeed lead out of the table.
>>
>> this happens around line 2809 of org-table.el, inside 
>> org-table--row-type
>>
>> I've tried to catch the user-error with a `condition-case', but even 
>> there, the error seems to happen before evaluation.
>>
>> I've replaced the `(user-error)' function with a `nil', and it works 
>> for me, but that's a very rough measure I'm afraid.
>>