20
votes
Accepted
sin of pi radians
The Emacs Lisp constant pi is not actually the number 𝜋. Rather, the Emacs Lisp constant pi is an approximation to 𝜋, good to about 16 digits -- pi is exactly 3....
- 216
6
votes
sin of pi radians
I think this is simply the expected answer. As a float, 1.2246467991473532e-16 is not different from zero, given the floating point error Emacs Lisp can handle. One get the same answer in R for ...
- 1,124
5
votes
Accepted
How to insert mathematical symbols in emacs
You can set the insert method with M-x set-input-method RET tex. Then type \beta and watch it get converted.
It can be toggled and set with C-\!
Tested and confirmed that it compiles and renders ...
- 536
5
votes
sin of pi radians
You are doing nothing wrong. This function is working with floating point numbers which have good, but limited, accuracy. 1.2246467991473532e-16 is pretty close to 0 (0.0... with 15 zeros before the ...
- 3,740
4
votes
Accepted
How can I convert a Lisp expression to a LaTeX math expression?
Here is a toy function:
(defvar lisp2latex-need-parens nil)
(defun lisp2latex (form)
(pcase form
(`(+ . ,args)
(let ((ret (let ((lisp2latex-need-parens nil))
(mapconcat #'...
- 5,958
4
votes
Accepted
Convert percent to decimal: (/ PERCENT 100)
Your workaround tells the whole story:
(/ 1 2) ;=> 0
(/ 1.0 2) ;=>0.5
With integers, emacs does integer arithmetic, with floats it does floating-point arithmetic.
See the Elisp manual, node ...
- 3,740
4
votes
Accepted
Cube root in elisp
There are a couple of ways:
(expt 8 (/ 1.0 3.0)) ⇒ 2.0
Or, if you want symbolic results:
(require 'calc-arith)
(calcFunc-pow 8 (calcFunc-inv 3)) ⇒ (float 2 0)
(calcFunc-pow 8 (calcFunc-inv (list 'x)))...
- 16.8k
4
votes
Accepted
How get decimal values?
Assuming you're happy with floating point arithmetic then you just need to make one of the numbers a float. e.g.:
(/ 15.0 6)
=> 2.5
Refer to C-hig (elisp)Arithmetic Operations
each of these ...
- 49.7k
3
votes
Using `string-to-number` causes rounding/precision issue for specific floating point values
What Every Programmer Should Know About Floating-Point Arithmetic is an excellent guide to understanding floating point numbers. I thoroughly recommend reading that in full -- I think it will answer ...
- 49.7k
3
votes
Accepted
How can you automatically translate fractions into their short unicode versions? e.g. ⅔
You could use prettify-symbols-mode with something, evaluable in your sratch buffer, like this:
(progn
(push '("2/3" . ?⅔) prettify-symbols-alist)
(prettify-symbols-mode -1)
(prettify-symbols-...
- 2,594
2
votes
How can you automatically translate fractions into their short unicode versions? e.g. ⅔
If you're willing to have the text change, you can use one of Emacs' many input methods. With e.g. rfc3145, you could type that as
&23
or with TeX it would be
\\frac23
Use C-\ to choose your ...
- 4,850
2
votes
Insert trigonometric function to org file
Yes, by using Latex and preview that. Have a read at the org-mode manual org-latex-preview section.
There are embedded formulae like $\sin(r) = 3\sin\left(\frac r3\right)-4\sin^3\left(\frac r3\right)$...
- 4,501
2
votes
Replace text with latex
Go to the beginning of your text and press C-M-%. That key sequence is bound to the command query-replace-regexp.
Give \([+-]?[0-9]+\|\_<[[:alpha:]]\)/\([+-]?[0-9]+\|[[:alpha:]]\_>\) as search ...
- 32.8k
2
votes
How to insert mathematical symbols in emacs
I love the accepted answer, but I also wanted to point out that you can insert unicode characters by name using C-x 8 RET. This will bring up a selection list in the minibuffer that lets you type the ...
- 263
1
vote
change environment in evil-tex
From the documentation, the environment keymap for multiline* is M.
So for example from inside your equation environment in evil-normal-state, you can change the equation environment to multiline* ...
- 11
1
vote
How do I convert a `matrix` in one form to a `matrix` in another form (like `bmatrix` environment)
I suggest you use Calc. You can set language mode to latex, temporarily by opening a Calc session, or permanently by saving the configuration in the calc.el file.
Enable calc-embedded when the point ...
- 2,134
1
vote
How do I convert a `matrix` in one form to a `matrix` in another form (like `bmatrix` environment)
EDIT
There is/was a bug in the replace-string-in-region function.
Using the newest version of that function, your code works alright, except for some unwanted newlines due to the first backslash in ...
- 6,633
1
vote
Accepted
LaTeX fragments look different to exported PDF (witharrows)
Thanks to @NickD I have found a solution.
The solution is to register a custom org-preview-latex-process and run pdflatex/lualatex twice for generating the latex preview image:
(setq luamagick '(...
- 33
1
vote
LaTeX fragments look different to exported PDF (witharrows)
[Not a complete answer: in the first part, I show the TeX file for the preview and identify the problematic component of the pipeline, but I don't know why that component misbehaves. In the second ...
- 28.2k
1
vote
Accepted
Key sequence to automatically make math-mode fragments in org-mode?
I have a yasnippet for this:
# -*- mode: snippet; require-final-newline: nil -*-
# name: math for Org
# key: $$
# binding: direct-keybinding
# --
\\($1\\) $0
I type $$ and get what you want: \(_\).
- 4,138
1
vote
Accepted
Use LaTeX accents with tex insert method
M-x describe-input-method RET tex RET will tell you the (somewhat depressing) news: lots of letters can be "hatted" but they are Latin letters only. Input methods are limited in the kind of ...
- 28.2k
1
vote
Accepted
Remove math fragments from buffer in org mode
Just use an C-u prefix:
From the docs:
(org-latex-preview &optional ARG)
Toggle preview of the LaTeX fragment at point.
If the cursor is on a LaTeX fragment, create the image and
overlay it over ...
- 1,007
1
vote
Accepted
Customize org babel execution command in C
Use the :flags or :libs header to pass flags to the compiler (or libraries to the linker):
#+begin_src C :libs -lm
#include <stdio.h>
#include <math.h>
int main(){
printf("Square = %f",...
- 28.2k
1
vote
Evaluate algebraic formula in the buffer in place
For reference I'm posting my solution based on wasamasa's answer:
(save-excursion
(beginning-of-line)
(if (re-search-forward " *=.*" (line-end-position) t)
(replace-match ""))
(end-of-...
- 1,190
1
vote
Accepted
Evaluate algebraic formula in the buffer in place
calc provides calc-eval for this kind of use, just pass it a string and receive a string result back.
- 22k
Only top scored, non community-wiki answers of a minimum length are eligible