Re: [PATCH] org-table: Add mode flag to enable Calc units simplification mode

[Daniele Nicolodi <daniele@grinta.net>]

On 20/10/2020 16:32, Daniele Nicolodi wrote:
> On 20/10/2020 16:19, Eric S Fraga wrote:
>> Hello again,
>>
>> Following up on myself.  I'm seeing some strange behaviour although unit
>> calculations are working nicely.  For instance, this table:
>>
>> #+begin_src org
>>   | stream   | a            | b            | c            | total        |   x_a |   x_b |   x_c |
>>   |          | <l>          | <l>          | <l>          | <l>          |   <r> |   <r> |   <r> |
>>   |----------+--------------+--------------+--------------+--------------+-------+-------+-------|
>>   | feed     | 1.05 mol/s   | 1.05 mol/s   |              | 2.10 mol / s | 0.500 | 0.500 |     0 |
>>   | effluent | 0.74 mol / s | 0.74 mol / s | 0.32 mol / s | 1.80 mol / s | 0.411 | 0.411 | 0.178 |
>>   ,#+TBLFM: $5=vsum($2..$4);uf2::$6=$2/$5;uf3::$7=$3/$5;uf3::$8=$4/$5;uf3::@4$2=(1-0.3)*@-1;uf2::@4$3=(1-0.3)*@-1;uf2::@4$4=@-1+0.3*@-1$-1;uf2
>> #+end_src
>>
>> does not seem to pay attention to the f3 mode in the last column, first
>> data row.
> 
> It is something related to how Calc computes the result. The f2 mode
> specifies the formatting for floating point values, however it seems
> that Calc treats the zero (from the missing value in the fourth column)
> divided by a float (from the value in the fifth column) as an integer
> and not as a float. This may be because the org substitutes a "0" for
> the missing value, thus an integer. Still, I am not sure dividing an
> integer by a float should result in an integer (I guess zero is special
> cased here).
> 
> If you change the formula for that field to:
> 
>   #+TBLFM: $8=$4*1.0/$5;uf3
> 
> to force the $4 field to be evaluated as a float (there are other ways
> to get the same effect) you get the expected result (I think).

There are other funny Calc behaviors: if an expression results in a
number with an unit where the numerical part is exactly 1, the printed
result looses the numerical part and only the units are printed.

Cheers,
Dan