# Populate table row with rate changes with one formula

I've got this Exhibit A in brute force for a rate that is halved after 10 minutes

``````#+NAME: ratetable
| 0 min | 10 min | 20 min | 30 min | 40 min | 50 min |
|  20.0 |    10. |     5. |    2.5 |   1.25 |  0.625 |
#+TBLFM: @2\$2=@2\$1/2::@2\$3=@2\$2/2::@2\$4=@2\$3/2::@2\$5=@2\$4/2::@2\$6=@2\$5/2
``````

What I'd really like is a way to put in just one starting value in the second row/first column and have the rest of the row populated without all the individual formulae per cell. Any ideas/docs talking about this sort of "amortize(?) the whole row/column" would be appreciated.

## 1 Answer

You can use a range formula for cases like this. The relevant section in the manual, which you can get to with `C-h i g (org) Field and range formulas`, says:

‘@1\$2..@4\$3=’

``````Range formula, applies to all fields in the given rectangular
range.  This can also be used to assign a formula to some but not
all fields in a row.
``````

That, combined with relative references (`C-h i g (org) References`) , allows to write the above set of formulas as a single formula:

``````#+TBLFM: @2\$2..@2\$> = @2\$-1/2
``````

In words: for every cell in the second row `@2`, starting with the second column `\$2`, and ending with the last column `\$>`, set its value to be the value of the cell in the second row but the previous column `\$-1`, divided by 2.