On Wed, Aug 17, 2011 at 3:35 AM, Nick Dokos <nicholas.dokos@hp.com> wrote:

> Matt Price <moptop99@gmail.com> wrote:
>
> > Hi,
> >
> > It's htat time of year again and I'm putting together course syllabi.  I
> would really love to be able
> > to dynamically calculate dates in a spreadsheet, e.g.:
> >
> > |Topic 1|Date1|Description1|
> > |Topic2|Above Date + 7| Description2|
> > |Topic3|Above Date + 7| Description3|
> >
> > Is there a way for me to do that?
>
> As usual in situations like this, you have to start things off with
> a field formula for the first date. The column formula then can be
> used to calculate all the *other* rows (field formulas override column
> formulas - see section 3.5.6, "Column formulas", in the org manual
> or evaluate (info "(org) Column formulas") to get there directly).
>
> | Topic 1 | <2011-08-17 Wed> | Description1 |
> | Topic2  | <2011-08-24 Wed> | Description2 |
> | Topic3  | <2011-08-31 Wed> | Description3 |
> #+TBLFM: @1$2=<2011-08-17> :: $2 = <@-1$2> + 7
>
> The column formula says: get the field from the row above and the same
> column (@-1$2), interpret it as a date (<..>) and add 7 (days) to it.
> The column formula can be simplified to $2 = <@-1> + 7.
>
> If you want to increment by e.g. 10 mins, the increment has to be
> calculated as a fraction of a day:
>
> | Topic 1 | <2011-09-18 Sun 10:20> | Description1 |
> | Topic2  | <2011-09-18 Sun 10:30> | Description2 |
> | Topic3  | <2011-09-18 Sun 10:40> | Description3 |
> #+TBLFM: @1$2=<2011-09-18 10:20> :: $2 = <@-1> + 10*(1/24*60))
>
>
> ah, supercool.  thank you!!

matt