|
|
IDL Reference Guide: Procedures and Functions |
|
The periodic function SIN returns the trigonometric sine of X.
Result = SIN(X)
Returns the double-precision floating-point, complex or single-precision floating-point value.
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.
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.
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 2p 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 p. |
IDL Online Help (March 06, 2007)