Vi(m) tip #2: Entering greek/math symbols using vim digraphs

Alec Jacobson

October 14, 2009

weblog/

Lately I have been taking computer science/math class notes using vim. Since typing LaTeX is too cumbersome and not readily intuitive (you have to typeset it). I just use plain text. This is fine until I need to quickly type strange letters/symbols. I can do this in vim using digraphs. To see a list of available digraphs, in normal mode type:

:digraphs

To enter a digraph in insert mode simply hit <ctrl>+k then the two symbols to create the digraph. So to make the greek capital phi, Φ, you'd hit (in insert mode)

<ctrl>kF*

Below is a table of useful math and computer science digraphs.

symbol description	symbol	unicode (decimal)	vim digraph (first type <ctrl>k)
plus minus	±	177	+-
squared (superscript 2)	²	178	2S
coproduct (big, tall Pi)	∏	8719	*P
summation (big, tall Sigma)	∑	8721	+Z
bullet operator (dot product)	∙	8729	Sb
(square) root	√	8730	RT
infinity	∞	8734	00
Greek Letters
Gamma	Γ	915	G*
Delta	Δ	916	D*
Theta	Θ	920	H*
Pi	Π	928	P*
Sigma	Σ	931	S*
Phi	Φ	934	F*
Psi	Ψ	936	Q*
Omega	Ω	937	W*
alpha	α	945	a*
beta	β	946	b*
gamma	γ	947	g*
delta	δ	948	d*
epsilon	ε	949	e*
eta	η	951	y*
theta	θ	952	h*
kappa	κ	954	k*
lambda	λ	955	l*
mu	μ	956	m*
pi	π	960	p*
rho	ρ	961	r*
sigma	σ	963	s*
sigma (alternative)	ς	962	*s
tau	τ	964	t*
phi*	φ	966	f*
psi*	ψ	968	q*
omega*	ω	969	w*
dagger (sword)	†	8224	/-
double dagger (double sword)	‡	8225	/=
left arrow*	←	8592	<-
up arrow	↑	8593	-!
right arrow	→	8594	->
down arrow	↓	8595	-v
Logic
for all (for any)	∀	8704	FA
partial differential (curled little d)	∂	8706	dP
there exists (backwards capital E)	∃	8707	TE
logical and	∧	8743	AN
logical or	∨	8744	OR
therefore (triangle of dots)	∴	8756	.:
because (upside-down triangle of dots)	∵	8757	:.
Sets
Null set, empty set, var nothing, capital O slash	∅	8709	/0
Null set, empty set, var nothing, capital O slash	Ø	216	O/
element of	∈	8712	(-
contains as member	∋	8715	-)
set intersect	∩	8745	(U
set union	∪	8746	U)
subset of (contained in)	⊂	8834	(C
superset of (contains)	⊃	8835	)C
subset of or equal to	⊆	8838	(_
superset of or equal to	⊇	8839	)_
concatenation, centered dot	∘	8728	Ob
Calculus
integral S	∫	8747	In
double integral S	∬	8748	DI
line integral S with circle	∮	8750	Io
Delta	∆	8710	DE
Nabla	∇	8711	NB
Equalities, inequalities, et al.
tilde operator (centered tilde, proportional)	∼	8764	?1
approximately equal to	≅	8773	?=
almost equal to	≈	8776	?2
not equal to	≠	8800	!=
less than or equal to	≤	8804	=<
greater than or equal to	≥	8805	>=

* I avoid these because they are double-width characters. In the document they are technically only one character put displayed they take up two character positions resulting in overlap in vim. Note: Greek letters are usually their Latin alphabet "equivalent" then star, with capitals taking capital (uppercase) Latin letters, likewise for lowercase. I included some (what I use most) here. Note:"Superscript" and "subscript" numbers are all [digit]S for Superscript and [digit]s for subscript. Note: If you don't find the character you want above, or by typing :digraphs and paging through supported digraphs, you can input a unicode character by its value in hex. Do this by typing <ctrl>v in insert mode then: u[4-hex-digit value] U[8-hex-digit value] Leading zeros may be omitted. Note: On some machines <ctrl>v means paste, in that case use <ctrl>q source Update: I found a useful list of unicodes for math symbols.