$ZSIN (ObjectScript)
Synopsis
$ZSIN(n)
Argument
| Argument | Description |
|---|---|
| n | Angle in radians ranging from Pi to 2 Pi (inclusive). Other supplied numeric values are converted to a value within this range. |
Description
$ZSIN returns the trigonometric sine of n. The result is a signed decimal number ranging from 1 to -1 (see note). $ZSIN(0) returns 0. $ZSIN($ZPI/2) returns 1.
$ZSIN (like all trigonometric functions) calculates its values based on pi rounded to the number of available decimal digits. Therefore, the value returned by $ZSIN($ZPI) is .000000000000000000462644 and $ZSIN($ZPI*2) is –.00000000000000000092529. For this reason you should not perform limit tests comparing these returned values to 0.
Argument
n
An angle in radians ranging from Pi to 2 Pi (inclusive). It can be specified as a value, a variable, or an expression. You can specify the value Pi by using the $ZPI special variable. You can specify positive or negative values smaller than Pi or larger than 2 Pi; InterSystems IRIS resolve these values to the corresponding multiple of Pi. For example, 3 Pi is equivalent to Pi, and negative Pi is equivalent to Pi.
A non-numeric string is evaluated as 0. For evaluation of mixed numeric strings and non-numeric strings, refer to Strings As Numbers in Using ObjectScript.
Examples
The following example permits you to compute the sine of a number:
READ "Input a number: ",num IF $ZABS(num)>(2*$ZPI) { WRITE !,"number is a larger than 2 pi" } ELSE { WRITE !,"the sine is: ",$ZSIN(num) } QUIT
The following example compares the results from InterSystems IRIS fractional numbers ($DECIMAL numbers) and $DOUBLE numbers. In both cases, the sine of pi is a fractional number (not 0), but the sine of pi/2 is set to exactly 1:
WRITE !,"the sine is: ",$ZSIN($ZPI) WRITE !,"the sine is: ",$ZSIN($DOUBLE($ZPI)) WRITE !,"the sine is: ",$ZSIN($ZPI/2) WRITE !,"the sine is: ",$ZSIN($DOUBLE($ZPI)/2)
In the following example, all $ZSIN functions return zero (0):
WRITE !,"the sine is: ",$ZSIN(0.0) WRITE !,"the sine is: ",$ZSIN(-0.0) WRITE !,"the sine is: ",$ZSIN($DECIMAL(0.0)) WRITE !,"the sine is: ",$ZSIN($DOUBLE(0.0)) WRITE !,"the sine is: ",$ZSIN($DECIMAL(-0.0)) WRITE !,"the sine is: ",$ZSIN($DOUBLE(-0.0)) WRITE !,"the sine is: ",$ZSIN(-$DECIMAL(0.0)) WRITE !,"the sine is: ",$ZSIN(-$DOUBLE(0.0))
This is true on all platforms, including AIX.
