ldots

ldots is a TeX/LaTeX command that produces a horizontal ellipsis in mathematical expressions. In LaTeX it is written as \ldots and typically renders as three dots aligned with the baseline, ensuring consistent spacing within math mode. It is commonly used to indicate continuation or omission in sequences and lists, for example A_1, A_2, \ldots, A_n or 1, 4, 9, \ldots, 16.

In contrast to other ellipsis styles, \ldots is designed for baseline alignment, whereas \cdots centers the dots on the math axis and \vdots provides a vertical ellipsis. This distinction matters for the visual rhythm of expressions such as sums, products, or arrays. The LaTeX community often uses additional forms from the amsmath package, such as \dots, \dotsc, \dotsi, and \dotso, which adapt spacing and punctuation to context.

Usage notes: In simple sequences, \ldots is appropriate, but for more complex lists or patterned items it may be preferable to rely on the amsmath contextual ellipses (\dots) or its specialized variants to ensure proper punctuation and spacing. When writing mathematics in plain text or when interoperability with Unicode is desired, the horizontal ellipsis character U+2026 can be used, but proper math typesetting with \ldots typically yields better typographic results.

See also: \cdots, \vdots, \dots, LaTeX, amsmath.