Re: [O] Calculating percentage

[Adonay Felipe Nogueira]

* If you want to calculate the percentage change

Say, from [last row, first column] to [current row, first column], that
is:

( current - last_in_table ) / last_in_table

Then do either one of the following:

a. Direct answer. Go below the table and insert (without the extra spaces):

   #+TBLFM: @2$2..@>>$2=relch(@>$1, $1) * 100

b. Detailed answer. Go to any place inside the table and press C-c ',
   and insert (without the extra spaces):

    @2$2..@>>$2=relch(@>$1, $1) * 100

    "@" is row specification, "$" is column specification, ".." selects
    a range. Digits after "@" and "$" are absolute references (but as
    far as I can tell, these digits only count after the horizontal
    lines), ">" or "<" after these are relative to the last and first
    (of the entire table, this as far as I can tell also includes rows
    of horizontal lines), respectively.

The advantages of using (b) over (a) are:

- You have a split, friendly --- and probably highlighted --- view of
  what you're doing.

- Multiple formulas can be inserted simply by breaking a line. In the
  case of (a), you would have to manually insert "::" for each new
  formula for a given cell or cell range. Note that inserting multiple
  "#+TBLFM:" in order to apply multiple formulas to the same table at
  once isn't right, only the first "#+TBLFM" is evaluated.

** Example

--8<---------------cut here---------------start------------->8---
|----------+------------|
|  Average | Percentage |
|----------+------------|
| 3.01E+00 | -96.950355 |
| 7.31E+00 | -92.593718 |
|----------+------------|
| 2.72E+01 | -72.441743 |
| 4.09E+01 | -58.561297 |
|----------+------------|
| 6.80E+01 | -31.104357 |
| 7.07E+01 | -28.368794 |
|----------+------------|
| 7.19E+01 | -27.152989 |
| 9.87E+01 |            |
|----------+------------|
#+TBLFM: @2$2..@>>$2=relch(@>$1, $1) * 100
--8<---------------cut here---------------end--------------->8---

* If you want to calculate the percentage of the new value compared to
  the old value

Such as:

current / last_in_table

Then use:

$1 / @>$1

Instead of:

relch(@>$1, $1)

** Example

--8<---------------cut here---------------start------------->8---
|----------+------------|
|  Average | Percentage |
|----------+------------|
| 3.01E+00 |  3.0496454 |
| 7.31E+00 |  7.4062817 |
|----------+------------|
| 2.72E+01 |  27.558257 |
| 4.09E+01 |  41.438703 |
|----------+------------|
| 6.80E+01 |  68.895643 |
| 7.07E+01 |  71.631206 |
|----------+------------|
| 7.19E+01 |  72.847011 |
| 9.87E+01 |            |
|----------+------------|
#+TBLFM: @2$2..@>>$2=($1 / @>$1) * 100
--8<---------------cut here---------------end--------------->8---

-- 
- [[https://libreplanet.org/wiki/User:Adfeno]]
- Palestrante e consultor sobre /software/ livre (não confundir com
  gratis).
- "WhatsApp"? Ele não é livre, por isso não uso. Iguais a ele prefiro
  GNU Ring, ou Tox. Quer outras formas de contato? Adicione o vCard
  que está no endereço acima aos teus contatos.
- Pretende me enviar arquivos .doc, .ppt, .cdr, ou .mp3? OK, eu
  aceito, mas não repasso. Entrego apenas em formatos favoráveis ao
  /software/ livre. Favor entrar em contato em caso de dúvida.