arc tangent

arc tangent [¦ärk ′tan·jənt]

(mathematics)

Also known as antitangent; inverse tangent.

For a numberx, any angle whose tangent equalsx.

For a numberx, the angle between -π/2 radians and π/2 radians whose tangent equalsx; it is the value atxof the inverse of the restriction of the tangent function to the interval between -π/2 and π/2.