To convert and simplify units in tables (was:LIterate programming with calc (help))

To convert and simplify units in tables (was:LIterate programming with calc (help))

[Ypo]

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Hi

I have found an alternative solution to this problem:

> Is it possible to express in a calc block some basic operations with 
> variables and non-predefined units?
>
>
> For example, if you wanted to build a code block that calculates how 
> much money costs
>
> a land with an Area of 300x300 m^2 at a price of 1 $/m^2.
>
>
> Would it be something like this?
>
> #+begin_src calc
>   a = 300 m
>   b = 300 m
>   Area = a*b
>   cost = 1 ($/m^2)
>   A*c
>
> #+end_src
>

The alternative way I am trying is using an org-table. It is not 
literate programming, but it is a spreadsheet with units ;D

| $ | a = 300 m        |
| $ | b = 300 m        |
| _ | Area             |
|   | 90000 m^2        |
| $ | cost = 1 USD/m^2 |
| _ | Payment          |
|   | 90000 USD        |
#+TBLFM: $Area=$a*$b::$Payment=$Area*$cost

(Below "Area" cell it is the result of a*b, and below "Payment" cell it 
is the result of Area*cost)


Now, in a more practical case, I have some problems with units:

| $ | E = 2141404.05 kg/cm^2          |
| $ | s_lim = 275  N/mm^2              |
| $ | s_lim = 2800  kg/cm^2            |
| $ | W = 10000 kg                     |
| $ | l = 65  cm                       |
| $ | I = 25166  cm^4                  |
| $ | Z = 1680  cm^3                   |
| _ | s                                |
|   | 386.90476 kg cm / cm^3           |
| _ | cs                               |
|   | 7.2369231 kg cm^3 / (cm^2 kg cm) |
#+TBLFM: $s=$W*$l/$Z::$cs=$s_lim/$s

Below "cs" cell it appears 7.2... and this should be an adimensional 
number (no units). Is it possible to simplify those units?

I have tried with:

| $ | E = 2141404.05  kg/cm^2 |
| $ | s_lim = 275  N/mm^2     |
| $ | s_lim = 2800  kg/cm^2   |
| $ | W = 10000 kg            |
| $ | l = 65  cm              |
| $ | I = 25166  cm^4         |
| $ | Z = 1680  cm^3          |
| _ | s                       |
|   | 386.90476 kg / cm^2     |
| _ | cs                      |
|   | #ERROR                  |
#+TBLFM: $s=uconvert($W*$l/$Z,kg / cm^2)::$cs=uconvert($s_lim/$s, )

where uconvert is defined as:

(defmath uconvert (v u)
   "Convert value V to compatible unit U."
   (math-convert-units v u))


But no luck, "cs" result is an ERROR. Is it feasible to get a value for 
"cs" with no units?


Best regards


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Re: To convert and simplify units in tables (was:LIterate programming with calc (help))

[Ihor Radchenko]

Ypo <ypuntot@gmail.com> writes:

> (defmath uconvert (v u)
>    "Convert value V to compatible unit U."
>    (math-convert-units v u))
>
>
> But no luck, "cs" result is an ERROR. Is it feasible to get a value for 
> "cs" with no units?

Note that apart from Calc formula notation, you can use Elisp. That will
avoid all the gotchas Calc has.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

Re: To convert and simplify units in tables (was:LIterate programming with calc (help))

[ypuntot]

Hi Ihor.
I'm null at elisp. Could you please refer to me a simple example of math operation and unit simplification in elisp?
Thanks :$

10 dic 2022 14:51:39 Ihor Radchenko <yantar92@posteo.net>:

> Ypo <ypuntot@gmail.com> writes:
> 
>> (defmath uconvert (v u)
>>   "Convert value V to compatible unit U."
>>   (math-convert-units v u))
>> 
>> 
>> But no luck, "cs" result is an ERROR. Is it feasible to get a value for
>> "cs" with no units?
> 
> Note that apart from Calc formula notation, you can use Elisp. That will
> avoid all the gotchas Calc has.
> 
> -- 
> Ihor Radchenko // yantar92,
> Org mode contributor,
> Learn more about Org mode at <https://orgmode.org/>.
> Support Org development at <https://liberapay.com/org-mode>,
> or support my work at <https://liberapay.com/yantar92>

Re: To convert and simplify units in tables

[Fraga, Eric]

On Sunday, 27 Nov 2022 at 20:19, Ypo wrote:
> The alternative way I am trying is using an org-table. It is not
> literate programming, but it is a spreadsheet with units ;D
> [...]
> Now, in a more practical case, I have some problems with units:
>
> | $ | E = 2141404.05  kg/cm^2          |
> | $ | s_lim = 275  N/mm^2              |
> | $ | s_lim = 2800  kg/cm^2            |
> | $ | W = 10000 kg                     |
> | $ | l = 65  cm                       |
> | $ | I = 25166  cm^4                  |
> | $ | Z = 1680  cm^3                   |
> | _ | s                                |
> |   | 386.90476 kg cm / cm^3           |
> | _ | cs                               |
> |   | 7.2369231 kg cm^3 / (cm^2 kg cm) |
>
> #+TBLFM: $s=$W*$l/$Z::$cs=$s_lim/$s

org tables do have support for units, based on Emacs Calc.  You need to
add the "u" option to the formulas for this support.  If I change your
formulas to:

#+TBLFM: $cs=$s_lim/$s;u::$s=$W*$l/$Z;u

everything seems to work just fine.  

-- 
: Eric S Fraga, with org release_9.6-14-g53814a in Emacs 30.0.50

To convert and simplify units in tables (was:LIterate programming with calc (help))

[Ypo]

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> #+TBLFM: $s=uconvert($W*$l/$Z,kg / cm^2)::$cs=uconvert($s_lim/$s, )
>
> where uconvert is defined as:
>
> (defmath uconvert (v u)
>   "Convert value V to compatible unit U."
>   (math-convert-units v u))
>
>
> But no luck, "cs" result is an ERROR. Is it feasible to get a value 
> for "cs" with no units?
>
Ok, it is enough to add any unit to uconvert, for example: 
$cs=uconvert($s_lim/$s,m). That simplifies units in adimensional parameters.

Best regards ;D

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