In mathematics, the signature of a metric tensor g (or equivalently, a real quadratic form thought of as a real symmetric bilinear form on a finite-dimensional vector space) is the number (counted with multiplicity) of positive, negative and zero eigenvalues of the real symmetric matrix of the metric tensor with respect to a basis. In relativistic physics, the v represents the time or virtual dimension, and the p for the space and physical dimension.

(time signatures)

A Signature drink is any unique or original drink that expresses the nature of the person or establishment creating it.

time signature. The time signature indicates that there are three quarter notes (crotchets) per measure (bar).

(signatories)

1. A set of function symbols with arities. 2. <messaging> (Or sig) A few lines of information about the sender of an electronic mail message or news posting. Most Unix mail and news software will automagically append a signature from a file called .signature in the user's {home directory} to outgoing mail and news. A signature should give your real name and your {e-mail address} since, though these appear in the headers of your messages, they may be munged by intervening software. It is currently (1994) hip to include the URL of your home page on the World-Wide Web in your sig. The composition of one's sig can be quite an art form, including an ASCII logo or one's choice of witty sayings (see sig quote, fool file). However, large sigs are a waste of bandwidth, and it has been observed that the size of one's sig block is usually inversely proportional to one's prestige on the net. See also doubled sig, sig virus. 2. <programming> A concept very similar to {abstract base classes} except that they have their own hierarchy and can be applied to compiled classes. Signatures provide a means of separating subtyping and inheritance. They are implemented in C++ as patches to GCC 2.5.2 by Gerald Baumgartner <gb@cs.purdue.edu>. ftp://ftp.cs.purdue.edu/pub/gb/. (2001-01-05)