# FX_SinIdx

## Syntax

      #include <nitro/fx/fx_trig.h>

      fx16 FX_SinIdx(int idx);

## Arguments

idx | The number of units with a value of 2π radians divided by 65536.

## Return Values

Approximation of the sine.

## Description

The argument equates 1 to the value of 2π radian divided by 65,536. It returns the result as an `fx16` type. It is based on a lookup in an internal 4,096-element table. Be aware that the error will become very large near 0 and π. The argument must take a value between 0 and 65535.

The argument is the `int` type, so in order to make the negative numbers and the numbers larger than 65536 to wrap around to be between 0 and 65536, it needs to be cast explicitly to an `u16` type or masked by 0xffff.

## See Also

`FX_CosIdx, FX_SinFx64c, FX_CosFx64c`

## Revision History

2004/06/16 Initial version.

CONFIDENTIAL