Desimaalipiste

Desimaalipiste, literally the decimal point, is the dot character "." used to separate the integer part from the fractional part in decimal notation. It functions as the decimal separator in contexts such as computing and international data exchange. In Finnish standard writing, the decimal separator is typically a comma (desimaalipilkku), so the desimaalipiste is mainly encountered in technical writing, programming, and when adhering to international conventions.

Examples of its use are familiar: 3.14, 0.001, -12.5. The dot marks the boundary between whole units and fractions in base-10 notation. In addition, numbers may include a trailing zero after the decimal point to indicate a floating-point value, as in 2.0.

In computing and digital data, the desimaalipiste is the standard decimal separator in many programming languages (for example Python, JavaScript, Java) and data formats such as JSON. Software locale settings can switch the decimal separator to a comma, which may require formatting adjustments when exchanging numbers with systems that use desimaalipiste.

The term helps distinguish the dot from the decimal comma. Its use reflects international conventions for numeric notation, where the period serves as the decimal separator in many countries and contexts, while a comma is used in others.