Apple Numbers '08 - Manual (Page 210)

210 Chapter 12 Dictionary of Functions
Notes
To see the resulting angle in degrees instead of radians, use the DEGREES function.
ATAN2
The ATAN2 function calculates the angle, relative to the positive x-axis, of the line
passing through the origin and the specified point. The angle is expressed in radians, in
the range –pi through pi.
ATAN(x, y)
 x: The x-coordinate of the point the line passes through.
 y: The y-coordinate of the point the line passes through.
Notes
To see the resulting angle in degrees instead of radians, use the DEGREES function.
ATANH
The ATANH function calculates the inverse hyperbolic tangent of a number.
ATANH(number)
 number: Any number between –1 and 1.
AVEDEV
The AVEDEV function calculates the average difference (deviation) of the data points
from their arithmetic mean (average).
AVEDEV(datapoint, [datapoint, . . .])
 datapoint: One or more numbers, numeric expressions, or references to cells
containing numbers or numeric expressions.
Examples
ATAN(1) returns the angle measure 0.785398163 radians (45 degrees), which has a tangent of 1.
DEGREES(ATAN(1)) returns 45.
Examples
ATAN2(1, 1) returns 0.78539816 radians (45 degrees), the angle of a line segment from the origin to
point (1,1).
DEGREES(ATAN2(5,5)) returns 45.
Examples
ATANH(0.995054753686731) returns 3.
ATANH(TANH(2)) returns 2.