$ZARCTAN (ObjectScript)
Synopsis
$ZARCTAN(n)
Argument
| Argument | Description |
|---|---|
| n | Any positive or negative number. |
Description
$ZARCTAN returns the trigonometric inverse (arc) tangent of n. Possible results range from 1.57079 (half of pi) through zero to –1.57079. The result is given in radians.
Argument
n
Any positive or negative number. It can be specified as a value, a variable, or an expression. You can use the $ZPI special variable to specify pi.
A non-numeric string is evaluated as 0. For evaluation of mixed numeric strings and non-numeric strings, refer to Strings As Numbers.
The following are arc tangent values returned by $ZARCTAN:
| n | Returned Arc Tangent |
|---|---|
| 2 | returns 1.107148717794090502 |
| 1 | returns .7853981633974483098 |
| 0 | returns 0 |
| -1 | returns -.7853981633974483098 |
Examples
The following example permits you to calculate the arc tangent of a number:
READ "Input a number: ",num
WRITE !,"the arc tangent is: ",$ZARCTAN(num)
QUITThe following example compares the results from InterSystems IRIS fractional numbers ($DECIMAL numbers) and $DOUBLE numbers. In both cases, the arc tangent of pi/2 is a fractional number (not 1), but the arc tangent of 0 is 0:
WRITE !,"the arc tangent is: ",$ZARCTAN(0.0)
WRITE !,"the arc tangent is: ",$ZARCTAN($DOUBLE(0.0))
WRITE !,"the arc tangent is: ",$ZARCTAN($ZPI)
WRITE !,"the arc tangent is: ",$ZARCTAN($DOUBLE($ZPI))
WRITE !,"the arc tangent is: ",$ZARCTAN($ZPI/2)
WRITE !,"the arc tangent is: ",$ZARCTAN($DOUBLE($ZPI)/2)
