Symbols:Numerical Analysis

Tolerance

$\pm$

Defines a range in which a number may lie.

$x = a \pm b$ means $a - b \le x \le a + b$.

In the context of engineering, it is known as a tolerance, arising from the idea that any number within $\pm b$ of $a$ is a within a tolerable range of the desired value.

(The despicable political term zero tolerance was supposedly coined as a reflection of the above engineering definition. It of course takes someone with an actual mathematical or engineering background to understand how poisonously unachievable such an aspiration is.)

Its $\LaTeX$ code is \pm.

See Arithmetic and Algebra for an alternative definition of this symbol.