Table formula references

[Manuel Schneckenreither <manuel.schnecki@gmail.com>]

Hi,

I'd like to use following formula on like this:

  | t | y_t | y_{t+1} |
  |---+-----+---------|
  | 1 | 115 |         |
  | 2 | 121 |         |
  | 3 | 118 |         |
  | 4 | 127 |         |

  $4 = \sum_{\tau=0}^{@#-2}{0.9^{\tau} * y_{@#-2-\tau}}
  

So that's a simple sum, which just iterates over the values and uses the
index for power and to get the value of y_{4-\tau}. So @5$3 should be
0.9^0*127 + 0.9^1*118 + 0.9^2*121 + 0.9^3*115. Shouldn't be too hard I
though, but I couldn't figure it out how to implement it using
org-spreadsheets.

As I need the index I tried using subscr with no success. I can
obviously generate the list of rows used for the calculation using
@2$1..@2$#. However, as soon as I use an elsip function in the formula I
struggle with the representation of the list:

#+TBLFM: $3='(mapcar '1+ (@2$1..@2$#))

shows following debug output:

   Substitution history of formula
   Orig:   '(mapcar '1+ (@2$1..@2$3))
   $xyz->  '(mapcar '1+ (@2$1..@2$3))
   @r$c->  '(mapcar '1+ (#("1" 0 1 (fontified t line-prefix #("******* " 0 7 (face org-indent)) wrap-prefix #("******* " 0 8 (face org-indent)) face org-table)) #("115" 0 3 (fontified t line-prefix #("******* " 0 7 (face org-indent)) wrap-prefix #("******* " 0 8 (face org-indent)) face org-table))))
   $1->    '(mapcar '1+ (#("1" 0 1 (fontified t line-prefix #("******* " 0 7 (face org-indent)) wrap-prefix #("******* " 0 8 (face org-indent)) face org-table)) #("115" 0 3 (fontified t line-prefix #("******* " 0 7 (face org-indent)) wrap-prefix #("******* " 0 8 (face org-indent)) face org-table))))
   Result: #ERROR
   Format: NONE
   Final:  #ERROR

Is there a simple way to do it? Do I need to go over elsip functions,
and if so. How can I properly use a list?

I couldn't find a way on the web.


Best regards

Manuel