## Integral signs

Integrals ∫ are mathematical text symbols (we will talk later about their meaning) that people had been texting from the times when ASCII encoding was developed. And you can type them right from your keyboard. I'll show you how to do it by using different techniques depending on your Operating System and tastes.

Maths | ∫ | ∬ | ∭ | ∯ |
---|---|---|---|---|

∮ | ∲ | ∳ | ∰ |

Maths Emoji | ➕ | ➖ |
---|---|---|

✖ | ➗ |

### Maths of integral

Given a function f of a real variable x and an interval [a, b] of the real line, the definite **Integral** is defined informally to be the area of the region in the xy-plane bounded by the graph of f, the x-axis, and the vertical lines x = a and x = b, such that area above the x-axis adds to the total, and that below the x-axis subtracts from the total.

Integration is usually denoted like:

∫f(x) dx

The integral sign ∫ represents integration. The *dx* indicates that we are integrating over *x*; *x* is called the variable of integration. In correct mathematical typography, the *dx* is separated from the integrand by a space. Inside the ∫...*dx* is the expression to be integrated, called the integrand. In this case the integrand is the function *f(x)*. Because there is no domain specified, the integral is called an indefinite integral.

### How to input integral symbols

Choose your system to find out.

Windows#### Shift States

Configure your keyboard layout in Windows so that you can type all additional symbols you want as easy as any other text. Takes about 5-10 minutes to set things up, but you'll be typing like a boss. You can assign mathematical integral symbol ∫ and any other text characters to your keyboard using this technique.

#### Character Map

CharMap allows you to view and use all characters and symbols available in all fonts (some examples of fonts are "Arial", "Times New Roman", "Webdings") installed on your computer. You can input integral symbols using it.

#### Emoji on iOS (iPhone, iPad and iPod touch)

#### Keyboard viewer

You can make frequently used technical non-fancy symbols like "√ ∑ π ∞ ∆ ™ © æ £ ¢" and åccénted letters on Mac using [Option] key. I've compiled a list of shortcuts in my article and explained how to open keyboard viewer. You can also use your Keyboard Viewer as an alternative to my list.

[Option] + [B] produces ∫ integral sign.

#### Character Palette

#### From Keyboard

Unicode hex code | Symbol |

222B | ∫ |

222C | ∬ |

222D | ∭ |

222E | ∮ |

2232 | ∲ |

2233 | ∳ |

222F | ∯ |

2230 | ∰ |

There actually are 3 different ways to type symbols on Linux with a keyboard. But only third and fourth level chooser keys and unicode hex codes can produce mathematical integral text symbols.

#### Character map

Character map allows you to view and use all characters and symbols available in all fonts (some examples of fonts are "Arial", "Times New Roman", "Webdings") installed on your computer. It can also help you lookup Unicode codes for entering symbols with keyboard.

Following is a list of HTML and JavaScript entities for integral symbols. In Javascript you should write like a = "this \u2669 symbol" if you want to include a special symbol in a string.

HTML entity | JS entity | Symbol |
---|---|---|

∫ | \u222b | ∫ |

∬ | \u222c | ∬ |

∭ | \u222d | ∭ |

∮ | \u222e | ∮ |

∲ | \u2232 | ∲ |

∳ | \u2233 | ∳ |

∯ | \u222f | ∯ |

∰ | \u2230 | ∰ |