# Arithmetic underflow

﻿
Arithmetic underflow

Arithmetic underflow (or "floating point underflow", "floating underflow", "underflow") is a condition that can occur when the result of a floating point operation would be smaller in magnitude (closer to zero, either positive or negative) than the smallest quantity representable. Underflow is actually (negative) overflow of the exponent of the floating point quantity. For example, an eight-bit two's complement exponent can represent multipliers of $2^\left\{-128\right\}$ to $2^\left\{127\right\}$. A result less than $2^\left\{-128\right\}$ would cause underflow.

Depending on the processor, the programming language and the run-time system, underflow may set a status bit, raise an exception, generate a hardware interrupt, or may cause some combination of these effects. Alternatively, the underflow may just be ignored and zero substituted for the unrepresentable value, although this might lead to a later division by zero error which cannot be so easily ignored.

As specified in IEEE 754 the underflow condition is only signaled if there is also a loss of accuracy. Typically this is determined as the final result being inexact. However if the user is trapping on underflow, this may happen regardless of consideration for loss of precision.

ee also

*Integer overflow

References

*

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Underflow — may refer to:* Buffer underflow, in computer science, a condition in which an attempt is made to read an empty buffer * Arithmetic underflow, in floating point arithmetic, a condition in which an intermediate result is strictly between zero and… …   Wikipedia

• Arithmetic overflow — The term arithmetic overflow or simply overflow has the following meanings. In a computer, the condition that occurs when a calculation produces a result that is greater in magnitude than that which a given register or storage location can store… …   Wikipedia

• Standard deviation — In probability and statistics, the standard deviation is a measure of the dispersion of a collection of values. It can apply to a probability distribution, a random variable, a population or a data set. The standard deviation is usually denoted… …   Wikipedia

• Signed zero — is zero with an associated sign. In ordinary arithmetic, −0 = +0 = 0. However, in computing, some number representations allow for the existence of two zeros, often denoted by −0 (negative zero) and +0 (positive zero). This… …   Wikipedia

• NaN — For other uses, see Nan. In computing, NaN (Not a Number) is a value of the numeric data type representing an undefined or unrepresentable value, especially in floating point calculations. Systematic use of NaNs was introduced by the IEEE 754… …   Wikipedia

• Soupassement arithmétique — Le terme soupassement arithmétique, soupassement en virgule flottante, soupassement de capacité ou tout simplement soupassement est un néologisme qui s inspire du mot dépassement. Le soupassement est parfois connu sous le nom anglais arithmetic… …   Wikipédia en Français

• −0 (number) — −0 is the representation of negative zero or minus zero, a number that, in computing, exists in some signed number representations for integers, and in most floating point number representations. In mathematical terms there is no concept of a… …   Wikipedia

• Analyse lexicale — L analyse lexicale se trouve tout au début de la chaîne de compilation. C est la tâche consistant à décomposer une chaîne de caractères en unités lexicales, aussi appelées tokens. Ces tokens, produits à la demande de l analyseur syntaxique, sont… …   Wikipédia en Français

• Analyse statique de programmes — En informatique, la notion d analyse statique de programmes couvre une variété de méthodes utilisées pour obtenir des informations sur le comportement d un programme lors de son exécution sans réellement l exécuter. C est cette dernière… …   Wikipédia en Français

• Analyse syntaxique — Pour les articles homonymes, voir Analyseur. L analyse syntaxique consiste à mettre en évidence la structure d un texte, généralement un programme informatique ou du texte écrit dans une langue naturelle. Un analyseur syntaxique (parser, en… …   Wikipédia en Français