1×3

1×3, read as “one by three,” is a common notation used to convey product, size, or dimension in mathematics and related fields. As a product, 1×3 equals 3.

In geometry, a 1×3 rectangle has dimensions 1 by 3, and its area is 3 square units. The orientation is interchangeable, so a 3×1 rectangle is equivalent in area, though its sides are swapped.

In linear algebra, a 1×3 matrix is a row vector with three entries. Its transpose is a 3×1 column vector, and such a matrix can represent a point in a three-dimensional space or define a linear functional depending on context.

In discrete geometry, a 1×3 tile, also known as an I-tromino, consists of three unit squares in a straight line. These tiles appear in tiling problems and can cover certain boards when dimensions are compatible (for example, a 1×n strip can be tiled by 1×3 trominoes when n is a multiple of 3).

In image processing and computer vision, a 1×3 kernel or filter is a small matrix with three weights used in convolution, typically applied horizontally to capture linear features along rows.

Notation and usage vary by domain, but 1×3 generally denotes a size, a product, or a structural dimension, with the core idea being a single unit in one dimension and three units in another.