(mathematics) The function whose value is zero if its independent variable is negative, and one otherwise.

(physics) A function of the position and spin of an electron; related to the probability of finding the electron in a specified position

(mathematics) Any function of a real variable whose value increases as the variable increases.

(astronomy) a relationship that specifies the mass distribution of a newly formed stellar population

The ratio of the Laplace transform of the primary feedback signal of a control system to that of the actuating signal

(mathematics) The logarithm of a trigonometric function

(computing) Any of a set of subroutines supplied with a language or system that can be called to perform standard mathematical functions efficiently

(physics) A relationship that describes the probability of a particle that collides with another being scattered in any particular manner

(mathematics) A function that gives the relative probability that a discrete random variable is exactly equal to some value.

(mathematics, physics) A function which specifies the average density of atoms, molecules etc in three dimensions from a given point.