Documentation STACK

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Free-text input

This input allows you to type in free text, e.g. your complete working or mathematical proof.

  1. You can type markdown text.
  2. You can type AsciiMath between backticks for mathematics: ...
  3. You can include LaTeX between brackets, ... for inline mathematics and ... displayed mathematics.
  4. Sometimes, but not always, you will be able to include calculations between {@...@}. Rather than reaching for an external calculator, the software will replace your requested calculation with the answer.

Mathematics

If you would like mathematical expressions/equations to be inline then use AsciiMath. For example

This problem asks us to solve `x^2-10x+9=0`, which is a quadratic equation.

If you would like mathematical expressions/equations to be displayed then also use AsciiMath, but put backticks `` on a single line at the start and end. For example

To solve `x^2-10x+9` we work line by line
`
x^2-10x+9
(x-5)^2-16=0
(x-5)^2-4^2=0
(x-5-4)(x-5+4)=0
(x-9)(x-1)=0
x=9 or x=1
`

If you have text on the same line as a backtick you will get inline mathematics.

Markdown

Markdown is a lightweight markup language for creating formatted text using a plain-text editor.

Here are some example of what you need to type to format text.

# Heading

## Sub-heading

Paragraphs are separated by a blank line.

Two spaces at the end of a line  
produce a line break.

Text attributes _italic_, **bold**.

Horizontal rule:

---

Bullet lists nested within numbered list:

  1. fruits
     * apple
     * banana
  2. vegetables
     - carrot
     - broccoli

In normal markdown backticks are used for monospace

   `monospace`

However free-text input uses backticks for AsciiMath, see below.

AsciiMath

AsciiMath is an easy-to-write markup language for mathematics. Most AsciiMath symbols attempt to mimic in text what they look like rendered, like oo for \infty. Many symbols can also be displayed using a LaTeX alternative (see below), but without a backslash.

Input

`sum_(k=1)^oo 1/k^2=pi^2/6`

is rendered as \sum_{k=1}^\infty \frac{1}{k^2} = \frac{\pi^2}{6}.

Operation symbols

Type See TeX alt
+ +
- -
* \cdot cdot
** \ast ast
*** \star star
// //
\\ \backslash backslash, setminus
xx \times times
-: \div div
|>< \ltimes ltimes
><| \rtimes rtimes
|><| \bowtie bowtie
@ \circ circ
o+ \oplus oplus
ox \otimes otimes
o. \odot odot
sum \sum
prod \prod
^^ \wedge wedge
^^^ \bigwedge bigwedge
vv \vee vee
vvv \bigvee bigvee
nn \cap cap
nnn \bigcap bigcap
uu \cup cup
uuu \bigcup bigcup


Miscellaneous symbols

Type See TeX alt
2/3 \frac{2}{3} frac{2}{3}
2^3 2^3
sqrt x \sqrt{x}
root(3)(x) \sqrt[3]{x}
int \int
oint \oint
del \partial partial
grad \nabla nabla
+- \pm pm
O/ \emptyset emptyset
oo \infty infty
aleph \aleph
:. \therefore therefore
:' \because because
|...| \ldots |ldots|
|cdots| \cdots
vdots \vdots
ddots \ddots
|\ | \
|quad| \quad
/_ \angle angle
frown \frown
/_\ \triangle triangle
diamond \diamond
square \square
|__ \lfloor lfloor
__| \rfloor rfloor
|~ \lceil lceiling
~| \rceil rceiling
CC \mathbb{C}
NN \mathbb{N}
QQ \mathbb{Q}
RR \mathbb{R}
ZZ \mathbb{Z}
"hi" \text{hi} \text{hi}


Relation symbols

Type See TeX alt
= =
!= \ne ne
< lt
> > gt
<= \le le
>= \ge ge
mlt \ll ll
mgt \gg gg
-< \prec prec
-<= \preceq preceq
>- \succ succ
> -= \succeq succeq
in \in
!in \notin notin
sub \subset subset
sup \supset supset
sube \subseteq subseteq
supe \supseteq supseteq
-= \equiv equiv
~= \cong cong
~~ \approx approx
prop \propto propto


Logical symbols

Type See TeX alt
and \land
or \lor
not \neg neg
=> \implies implies
if \text{if}
<=> \iff iff
AA \forall forall
EE \exists exists
_|_ \bot bot
TT \top top
|-- \vdash vdash
|== \models models


Grouping brackets

Type See TeX alt
( (
) )
[ [
] ]
(: \langle langle
:) \rangle rangle
<< \langle\langle
>> \rangle\rangle
floor(x) \lfloor x \rfloor
ceil(x) \lceil x \rceil
norm(vecx) \left
  \vec{x} \right| |

Note, you can also use {...} for curly braces and abs(x) for |x|.

Arrows

Type See TeX alt
uarr \uparrow uparrow
darr \downarrow downarrow
rarr \rightarrow rightarrow
-> \to to
>-> \rightarrowtail rightarrowtail
->> \twoheadrightarrow twoheadrightarrow
\|-> \mapsto mapsto
larr \leftarrow leftarrow
harr \leftrightarrow leftrightarrow
rArr \Rightarrow Rightarrow
lArr \Leftarrow Leftarrow
hArr \Leftrightarrow Leftrightarrow


Accents

Type See TeX alt
hat x \hat{x}
bar x \overline{x} overline x
ul x \underline{x} underline x
vec x \vec{x}
tilde x \tilde{x}
dot x \dot{x}
ddot x \ddot{x}
overset(x)(=) \overset{x}{=} overset(x)(=)
underset(x)(=) \underset{x}{=}
ubrace(1+2) \underbrace{1+2} underbrace(1+2)
obrace(1+2) \overbrace{1+2} overbrace(1+2)
overarc(AB) \overparen{AB} overparen(AB)
color(red)(x) \color{red}{x}
cancel(x) \cancel{x}


Greek Letters

Type See Type See
alpha \alpha
beta \beta
gamma \gamma Gamma \Gamma
delta \delta Delta \Delta
epsilon \epsilon
varepsilon \varepsilon
zeta \zeta
eta \eta
theta \theta Theta \Theta
vartheta \vartheta
iota \iota
kappa \kappa
lambda \lambda Lambda \Lambda
mu \mu
nu \nu
xi \xi Xi \Xi
pi \pi Pi \Pi
rho \rho
sigma \sigma Sigma \Sigma
tau \tau
upsilon \upsilon
phi \phi Phi \Phi
varphi \varphi
chi \chi
psi \psi Psi \Psi
omega \omega Omega \Omega


Font commands

Type See TeX alt
bb "AaBbCc" \mathbf{AaBbCc} mathbf "AaBbCc"
bbb "AaBbCc" \mathbb{AaBbCc} mathbb "AaBbCc"
cc "AaBbCc" \mathcal{AaBbCc} mathcal "AaBbCc"
tt "AaBbCc" \mathtt{AaBbCc} mathtt "AaBbCc"
fr "AaBbCc" \mathfrak{AaBbCc} mathfrak "AaBbCc"
sf "AaBbCc" \mathsf{AaBbCc} mathsf "AaBbCc"


Standard Functions: sin, cos, tan, sec, csc, cot, arcsin, arccos, arctan, sinh, cosh, tanh, sech, csch, coth, exp, log, ln, det, dim, mod, gcd, lcm, lub, glb, min, max, f, g.

Special Cases

  • Matrices: [[a,b],[c,d]] yields to \begin{bmatrix} a & b \\ c & d \end{bmatrix}

  • Column vectors: ((a),(b)) yields to \begin{pmatrix} a \\ b \end{pmatrix}

  • Augmented matrices: [[a,b,|,c],[d,e,|,f]] yields to \left[\begin{array}{cc|c} a & b & c \\ d & e & f \end{array}\right]

  • Matrices can be used for layout: {(2x,+,17y,=,23),(x,-,y,=,5):} yields

 \left\{\begin{array}{ccccc} 2x & + & 17y & = & 23 \\ x & - & y & = & 5 \end{array}\right.

  • Complex subscripts: lim_(N->oo) sum_(i=0)^N yields to \lim_{N \to \infty} \sum_{i=0}^{N}

  • Subscripts must come before superscripts: int_0^1 f(x)dx yields to \int_{0}^{1} f(x),dx

  • Derivatives: f'(x) = dy/dx yields f'(x) = \frac{dy}{dx}

    For variables other than x, y, z, or t you will need grouping symbols: (dq)/(dp) yields \frac{dq}{dp}

  • Overbraces and underbraces: ubrace(1+2+3+4)_("4 terms") yields \underbrace{1+2+3+4}_{\text{4 terms}}

    obrace(1+2+3+4)^("4 terms") yields \overbrace{1+2+3+4}^{\text{4 terms}}

  • Attention: Always try to surround the > and < characters with spaces so that the HTML parser does not confuse them with opening or closing tags.

Full syntax is elsewhere.

LaTeX

LaTeX is a software system for typesetting documents. We support the mathematics environments between brackets, ... for inline mathematics and ... displayed mathematics. This leaves dollars $ for currency.

Calculations

When activated in a particular question, calculations between {@...@} will be automatically completed for you, rather than reaching for an external calculator.

  1. Type simple expressions using brackets for function arguments.
  2. Note angles are always in radians. E.g. try {@cos(pi)@} for example.
  3. Answers are given as floating point numbers, and you should choose the precision needed. E.g. {@round(cos(2),3)@}

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Licence Creative CommonsLa documentation STACK est soumise à la licence Creative Commons Attribution-ShareAlike 4.0 International.