From: Christian Moe <mail@christianmoe.com>
To: emacs-orgmode@gnu.org
Cc: Ihor Radchenko <yantar92@posteo.net>, Ypo <ypuntot@gmail.com>
Subject: Re: LIterate programming with calc (help)
Date: Mon, 24 Oct 2022 13:43:54 +0200 [thread overview]
Message-ID: <87zgdlwio5.fsf@christianmoe.com> (raw)
In-Reply-To: <87sfjd35xh.fsf@ucl.ac.uk>
Fraga, Eric writes:
> On Monday, 24 Oct 2022 at 09:20, Ihor Radchenko wrote:
>> I vaguely recall that storing variables in calc is something like
>> variable := assignment (which is actually rewrite rule, but that's how
>> 13.1 Storing Variables section of the calc manual explains variable
>> assignments).
>
> That is true for embedded calc (which I use all the time) but I cannot
> seem to get this to work for src blocks:
Same: it requires using the `s s' (calc-store) command, though (which
can also be done without the := assignment operator), and I've searched
the manual without spotting a way to do that with algebraic entry and
hence in a src block, as there doesn't seem to be any corresponding
command. I hope there is a way, though!
As an unsatisfying workaround, one could use :var header arguments; they
work up to a point, but not with units, as Ypo wants to use (and which
are are a really cool thing about Calc).
Once one's using variables, it will probably be necessary to wrap the
final calculation in evalv() to get a numeric value as output instead of
a formula with the variable names in it.
Another obstacle to what Ypo is trying to do is the attempt to use the $
sign for the currency unit. Calc does not have pre-defined currency
units, and $ is taken - it refers to the last value on stack. I tend to
use 'USD'.
So a partial, if pointless, way to do this would be to first store the
variables with the calculator:
' 300 m
s s a # store a = 300 m
' 300 m
s s b # store b = 300 m
' 1 USD/m^2
s s cost # store cost = (1) usd/m^2
' a*b
s s Area # store Area = a*b (*not* 90000 m^2)
Then the last step could be done in a src block:
#+begin_src calc
evalv(Area * cost)
#+end_src
#+RESULTS:
: 90000 USD
(Another cool bit: If you change the value of a or b and rerun the src
block, the result will change, since what was stored in Area was the
product of the variables, not the product of their values.)
Yours,
Christian
next prev parent reply other threads:[~2022-10-24 11:48 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-23 12:15 LIterate programming with calc (help) Ypo
2022-10-24 7:56 ` Fraga, Eric
2022-10-24 9:20 ` Ihor Radchenko
2022-10-24 9:51 ` Fraga, Eric
2022-10-24 11:43 ` Christian Moe [this message]
2022-10-24 11:26 ` Ypo
2022-10-24 15:25 ` Fraga, Eric
2022-10-31 9:23 ` Ihor Radchenko
2022-10-31 9:54 ` Fraga, Eric
2022-11-01 7:22 ` Ihor Radchenko
-- strict thread matches above, loose matches on Subject: below --
2022-11-26 20:16 Ypo
2023-09-10 13:06 Literate " Ypo
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