ATN

Arc Tangent

This numeric function returns the arc tangent of an angle in radians. In other words, ATN returns the angle, in radians, whose tangent is given.

Syntax

ATN (numeric-value [,ERR=line-ref|,ERC=error-code])

numeric-value: is any valid number from +/-.9999999999999E-57 through +/-.9999999999999E+58.
line-ref: is the program line number or label to branch to if an error is produced by this function.
error-code: is a programmer-defined error code. Valid values are positive or negative whole numbers.

This function returns a number that ranges from -1.57 through +1.57 (-Pi/2 to +Pi/2).

Note that ATN and TAN are reverse functions; that is:

ATN (TAN(x))=x
TAN (ATN(x))=x

ATN (0)

The result is 0.

ATN (1)

The result is .79 (i.e., Pi/4).

ATN (-100)

The result is -1.56.

These examples assume PRECISION 2.