We'd like to use analytics cookies to understand which symbols people look up, so we know what to research next. They are not used for advertising and we set none of them unless you say yes. What we store.
Two pairs of vertical strokes separated by a serif that vanishes at small sizes.
Determinant bars are plain vertical strokes with nothing at either end. Floor and ceiling brackets are vertical strokes with a short foot or cap on one end only, and which end carries the serif says which way the number is rounded — feet at the bottom for the floor, caps at the top for the ceiling. At small type sizes and in handwriting the serif is the first thing lost, which is the whole of the confusion.
Both are pairs of vertical strokes flanking an expression; the short serif is the only difference.
Drawn from the visual attributes recorded for each symbol. Only traits the two records disagree about are listed.
| Trait | Determinant bars | Floor and ceiling brackets |
|---|---|---|
| Built from | lines and dots, number like | lines and dots, squares |
| Symmetry | vertical | none |
| Determinant bars | Floor and ceiling brackets | |
|---|---|---|
| Ends of the stroke | Plain, no serif at either end | A short foot at the bottom, or a short cap at the top |
| Operation | Determinant, absolute value, length or cardinality by context | Round down, or round up, to a whole number |
| Applies to | A matrix, a number, a vector or a set | A real number |
| Relationship (from Symbolwise's records) | Commonly confused with Floor and ceiling brackets — Both are pairs of vertical strokes flanking an expression; the short serif is the only difference. | Commonly confused with Determinant bars — Both are pairs of vertical strokes flanking an expression. |
ISO 80000-2:2019, Quantities and units — Part 2: Mathematics
International Organization for Standardization · retrieved 2026-07-31
Paywalled and NOT READ for this batch. Registered so the standard can be named as existing and as covering mathematical signs; it supports no meaning in any record. See docs/paywalled-standards.md.
Unicode Code Chart: Mathematical Operators (U+2200–U+22FF)
The Unicode Consortium · retrieved 2026-07-30
Authoritative for the character's code point, name and block only. Unicode assigns identity; it does not define what a symbol means in use.
Brackets — square or round, the choice is house style — enclose a matrix: a rectangular array of entries. Straight vertical bars around the same grid denote its determinant, which is one number derived from the array. Swapping the delimiters therefore changes what has been written from a table into a scalar, and it is the commonest notational error in early linear algebra because the contents are identical and only the edges differ.
Alpha is a Greek letter and stands for a quantity — an angle, a coefficient, a significance level. The proportionality sign is an operator and stands between two quantities to say they keep a constant ratio. The drawings differ in that the proportionality sign's right-hand stroke runs out in an open curve rather than closing into the letter's tail.
Look at the left-hand edge. A straight flat back is an AND gate: the output is true only when every input is. A curved concave back is an OR gate: true when any input is. Everything else about the shapes is similar, which is why the back edge is worth checking deliberately rather than at a glance.
Look at what follows. A prefix never stands alone — it is glued to a unit symbol, as in kW or kg. A constant stands by itself in an equation. Careful physical writing subscripts the constant as k_B for exactly this reason, and the kelvin's capital K is a third claimant to the same letter.