# Catext Help

In this reference manual you will find detailed information on every aspect of Catext. If there is no answer for your question here, feel free to send an email.

## General Syntax

There are three types of elements in Catext: expressions, text and comments. Basically, anything that's not text or a comment is an expression.

## Expressions

Expressions define operations to perform on numbers, the result of which is then calculated by Catext. Numbers are the basic building block for expressions:

1 // integer

1.2 // decimal fraction

1.2e3 // exponential notation

1.2M = 1.2e6 // SI metric prefixes

1Ki = 1 024 // IEC binary prefixes

To resolve the ambiguity between `E` used as a SI metric prefix (exa) and `E` used to express a number in exponential notation, just add spaces: {1E−2} vs {1E − 2}.

Catext supports the standard basic set of arithmetic operations:

1 + 2 = 3 // addition

3 − 1 = 2 // subtraction

2 × 3 = 6 // multiplication

3 / 2 = 1.5 // division

Parentheses can be used to change the default order of operations:

2 × (1 + 3) = 8

The basic set is extended with the following operations:

2 % 3 = 2 // modulo/remainder

3^2 = 9 // exponentiation/power

If you are facing an ambiguity between `%` used as an operator and as a percent sign, pad `%` with spaces to make it behave like an operator: {1% + 1} vs {1 % +1}.

Exponentiation is right-associative: {4^3^2} means {4^(3^2)}.

### Variables

Variables are defined using the equal sign:

gross = 50k

tax = 20%

After the definition, variables can be referenced by their names:

gross − tax = 40k

Variables can be defined in terms of other variables:

net = gross − tax = 40k

net / 12 ≈ 3.333k

You can use multiple words in a variable name:

monthly net = net / 12 ≈ 3.333k

monthly net / 30 ≈ 111.111

Here are some more examples of valid variable names:

some_variable = 123

variable2 = 5

anotherVariable = 1

THE VARIABLE = 0 / 0

Catext provides autocompletion for variables, use Tab key to accept a completion.

### Percentages

Catext supports the following basic percentage operations:

200 + 10% = 220 // 10% more

200 − 10% = 180 // 10% less

200 × 10% = 20 // 10% of 200

10% + 20% = 30% // addition

10% − 20% = −10% // subtraction

10% / 2 = 5% // division

10% × 2 = 20% // multiplication

More advanced percentage operations are also supported:

// compound percentage

10% × −5% ≈ 4.5%

200 × (10% × −5%) ≈ 9

// effective annual percentage

(10% / 12)^12 ≈ 10.471%

1 000 + (10% / 12)^(5 × 12) ≈ 1 645.309

### Built-in Constants and Functions

The following built-in constants and functions are supported:

π ≈ 3.142 // `pi`

e ≈ 2.718 // Euler's number

abs(−1) = 1 // absolute value

round(π) = 3 // round to nearest

floor(π) = 3 // round down

ceil(π) = 4 // round up

int(π) = 3 // integer part

frac(π) ≈ 0.142 // fractional part

ln(e) = 1 // natural logarithm

log(e) = 1

lg(100) = 2 // base 10

log₁₀(100) = 2 // `log10(100)`

lb(8) = 3 // base 2

log₂(8) = 3 // `log2(8)`

sin(π / 2) = 1 // sine

asin(1) ≈ 1.571

arcsin(1) ≈ 1.571

cos(π) = −1 // cosine

acos(−1) ≈ 3.142

arccos(−1) ≈ 3.142

tan(π / 4) = 1 // tangent

atan(1) ≈ 0.785

arctan(1) ≈ 0.785

## Text

Lines starting with an uppercase letter and containing at least 3 words separated by spaces or commas are considered paragraphs. The familiar Markdown-like formatting is supported inside text:

• *italic* or _italic_

• **bold** or __bold__

• ***bold italic*** or ___bold italic___

• **_bold italic_ inside bold**

• \*escaping\*

• `preformatted: *regular*`

As an extension, you can also embed expressions into text using braces: {1 + 1}.

### Lists

Numbered list items begin with an integer number, followed by a dot and then by a space. Use `?. ` to automatically assign a number to an item. The second item is automatically numbered in the following list:

1. first item

2. second item

Bulleted list items begin with `-`, `*`, `+` or `?` followed by a space:

• bullet

+ pros

- cons

? investigate

## Comments

Line comments start with `//`, any following text until the end of the line is considered a comment:

// calculate 2

1 + 1 = 2 // should be 2

Comments support Markdown-like formatting. If you want to disable the formatting, just omit the space after `//`:

// this comment is **formatted**

//this comment is **not** formatted