# $ZCOS

## Synopsis

$ZCOS(n)

### Parameter

Argument | Description |
---|---|

n | An angle in radians ranging from Pi to 2 Pi (inclusive). Other supplied numeric values are converted to a value within this range. |

## Description

$ZCOS returns the trigonometric cosine of n. The result is a signed decimal number ranging from -1 to +1. $ZCOS(0) returns 1. $ZCOS($ZPI) returns -1.

## Parameter

### 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, negative Pi is equivalent to Pi, and zero is equivalent to 2 Pi.

A non-numeric string is evaluated as 0.

## Examples

The following example permits you to compute the cosine of a number:

READ "Input a number: ",num IF $ZABS(num)>(2*$ZPI) { WRITE !,"number is a larger than 2 pi" } ELSE { WRITE !,"the cosine is: ",$ZCOS(num) } QUIT

The following example compares the results from InterSystems IRIS fractional numbers ($DECIMAL numbers) and $DOUBLE numbers. In both cases, the cosine of 0 is exactly 1, the cosine of pi is exactly -1:

WRITE !,"the cosine is: ",$ZCOS(0.0) WRITE !,"the cosine is: ",$ZCOS($DOUBLE(0.0)) WRITE !,"the cosine is: ",$ZCOS(1.0) WRITE !,"the cosine is: ",$ZCOS($DOUBLE(1.0)) WRITE !,"the cosine is: ",$ZCOS($ZPI) WRITE !,"the cosine is: ",$ZCOS($DOUBLE($ZPI))