On Sun, Jun 1, 2014 at 12:00 PM, Cecil Westerhof <cldwesterhof@gmail.com> wrote:

> 2014-06-01 11:50 GMT+02:00 Cecil Westerhof <cldwesterhof@gmail.com>:
>> I am trying the following:
>>     #+TBLFM: @-I$4..@+I$4 = if("$3" == "nan", string(""), $3 - $2) ; %.1f
>> and:
>>     #+TBLFM: @-I$4..@+I$4 = if("$3" == "", string(""), $3 - $2) ; %.1f
>>
>> But in both case the fourth field is filled when the third field is empty.
>> What am I doing wrong?
>>
>> I am using version 8.2.1.
>
> The following does work:
>     #+TBLFM: @-I$4..@+I$4 = if($3 - $2 == -$2, string(""), $3 - $2) ;
>
> But is not what is described.
>
> I removed
>     %.1f
> because that displays an empty string as 0.0.
>
> Is it possible to use %.1f without making an empty field displayed as 0.0?

I suggest that I will improve the TBLFM example about "nan" in the
manual like this:

    `if("$1" == "nan" || "$2" == "nan", string(""), $1 + $2); E f-1'
         Sum of the first two columns.  When at least one of the input
         fields is empty the Org table result field is set to empty.  `E'
         is required to leave empty fields without conversion to 0.  `f-1'
         is an optional Calc format string similar to `%.1f' but leaves
         empty results empty.

Would this have answered all your questions?