# ISO 80000-2

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ISO 80000-2:2009 is a standard describing mathematical signs and symbols developed by the International Organization for Standardization (ISO), superseding ISO 31-11 [1] The Standard, whose full name is Quantities and units — Part 2: Mathematical signs and symbols to be used in the natural sciences and technology, is a part of the group of standards called ISO/IEC 80000.

## Contents list

The Standard is divided into the following chapters:

• Foreword
• Introduction
1. Scope
2. Normative references
3. Variables, functions, and operators
4. Mathematical logic
5. Sets
6. Standard number sets and intervals
7. Miscellaneous signs and symbols
8. Elementary geometry
9. Operations
10. Combinatorics
11. Functions
12. Exponential and logarithmic functions
13. Circular and hyperbolic functions
14. Complex numbers
15. Matrices
16. Coordinate systems
17. Scalars, vectors, and tensors
18. Transforms
19. Special functions
• Annex A (normative) - Clarification of the symbols used
• Bibliography

## Symbols for variables and constants

Clause 3 specifies that variables such as x and y, and functions in general (e.g., ƒ(x)) are printed in italic type, while mathematical constants are in roman (upright) type. Examples given of mathematical (upright) constants are e, π and i. The numbers 1, 2, 3, etc. are also upright.

## Function symbols and definitions

Clause 13 defines trigonometric and hyperbolic functions such as sin and tanh and their respective inverses arcsin and artanh.