The periodic function SIN returns the trigonometric sine of X.

## Examples

To find the sine of 0.5 radians and print the result, enter:

PRINT, SIN(0.5)

The following example plots the SIN function between 0 and 2π with 100 intervals:

X = 2*!PI/100 * FINDGEN(100)

PLOT, X, SIN(X)

**Note: **!PI is a read-only system variable that contains the single-precision value for π.

## Syntax

*Result* = SIN(*X*)

## Return Value

Returns the double-precision floating-point, complex or single-precision floating-point value.

## Arguments

### X

The angle for which the sine is desired, specified in radians. If *X* is double-precision floating or complex, the result is of the same type. All other types are converted to single-precision floating-point and yield floating-point results. When applied to complex numbers:

SIN(*x*) = (EXP(*i**x) - 1/EXP(*i**x))/(2**i*)

where *i* is defined as COMPLEX(0, 1).

If input argument *X* is an array, the result has the same structure, with each element containing the sine of the corresponding element of *X*.

## Keywords

### Thread Pool Keywords

This routine is written to make use of IDL’s *thread pool*, which can increase execution speed on systems with multiple CPUs. The values stored in the !CPU system variable control whether IDL uses the thread pool for a given computation. In addition, you can use the thread pool keywords TPOOL_MAX_ELTS, TPOOL_MIN_ELTS, and TPOOL_NOTHREAD to override the defaults established by !CPU for a single invocation of this routine. See Thread Pool Keywords for details.

## Version History

Original |
Introduced |